Foundation coursework

Isolating mechanism is the background factor for speciation to occur. Isolating mechanisms are barriers that prevent interbreeding of species due to geographical, structural, or behavioural factors of the species involved. Speciation is an evolutionary trend by which new species with a particular trait originates. (About.com, 2010). This essay will feature the forms of isolating mechanism and the role each play in the evolution of new species. It will also feature on the driving force of speciation and feature some types of speciation.

These barriers to gene flow are classified into two main groups: pre-zygotic and post-zygotic isolation. The former occurs before fertilization where gametes never meet and so do not form zygotes where as the later occurs after fertilization where the zygote formed may be inviable or sterile. These barriers may be because of geographical isolation, ecological isolation, behavioural isolation, temporal isolation or mechanical isolation (for pre-zygotic isolation), and hybrid inviabiability or hybrid sterility (for post-zygotic isolation). (Geology rock, 2009).

New species evolve because of the effects of natural selection, mutation, genetic drift, or absence of gene flow. (Nicholas et al, 2007). These effects set in when the above barriers occurs to function in the evolution of new species. Population divergence caused by natural selection can be as a result of habitat used, food preferences, or other ecological differences (Scott et al, 2007). These new species evolve as a result of allopatric speciation, where a population is separated by geographic barrier and so diverge in complete independence. It may be as a result of sympatric speciation where there is the absence of barrier and so occur from genetic differences, and finally, paratric speciation. (Nicholas et al, pg.645, 2007).

Geographical isolation plays a role in allopatric speciation where the population are separated by certain barriers such as mountain, continental drift, ranges, water bodies, etc. Once this occurs, gene flow is stopped, consequently resulting to mating incompatibility. Examples can be observed in a fresh water fish; Salvelinus spp., in Switzerland, Great Britain, and Scandinavia which do not interbreed. Temporal isolation also plays a role in the evolution of new species. This occurs when there is a difference in the mating season or reproductive cycle of population. Therefore, the population fails to meet though they live in the same habitat. A perfect example can be found in Pinus radiate and Pinus muricata, which grow in California. They each shed their pollens at different seasons of the year. Behavioural isolation also takes part in the evolution of a species. Here, though the population meets, but one fails to recognise the other`s courtship display due to differences in receptiveness to mating. This occurs in the cricket (Gryllus assimilis) population where the females fail to respond to the mating song of the males (Geology rock, 2009).

In mechanical isolation, though the population inhabits the same area, there is the problem of incompatibility of their genitals or reproductive organs due to shapes and sizes. A more realistic example could be found in species of genus Drosophila that shows some similarities except in their genital anatomy. Therefore, males cannot mate with some opposite sex from other species. Ecological isolation also plays an important role in the evolution of new species. Though the population lives in the same habitat, they occupy different ecological niches and therefore, never meet. Lion (Panthera leo) and tiger (Panthera tigris) are perfect examples of ecological isolation. They fail to meet because they occupy separate niches (Bio Ed Online, 2010).

Again, in hybrid inviability, the population meet and interbreed but the hybrid offspring fails to reach maturity and so dies at an early age. This occurs in the crosses between goats and sheep. Though fertilization takes place, the embryo dies in the early developmental stage. Hybrid sterility also helps in the evolution of new species. This occurs when species cannot reproduce caused by the segregation of aneuploid gametes during meiosis and also caused by the differences in the genes of the two parents. Therefore, the offspring produced is sterile. This occurs in the cross between Drosophila pseudoobscura from California and Utah, which shows the sterility of the hybrid offspring. (Geology rock, 2009).

In conclusion, both pre-zygotic and post-zygotic isolating mechanisms play vital roles in the evolution of new species. The both caused natural selection, population divergence, genetic drift, mutation, and absence of gene flow, which eventually lead to the evolution of the affected population into to new species. Allopatric speciation is caused by geographical isolation whereas paratric and sympatric speciation are as a result of other factors of mechanical isolation. In allopatric speciation, speciation occurs due to population divergence, which is caused by natural selection. In addition, sympatric speciation is as a result of genetic drift where two gametes may fuse but fail to pair up to form bivalent meiosis (Nicksnowden, n.d). The females` choice also play a role in the evolution of new species as observed in behavioural isolation where the females fail to recognise the courtship display of the males. Although population may be confined in a habitat, but fails to meet due to the location (niche) of the species(ecological isolation); receptiveness or time of activity of the species(temporal isolation); courtship behaviour and response(behavioural isolation); offspring inviability(hybrid inviability) and gene mutation or genetic drift(hybrid sterility).

References and bibliography

  • About.com (2010) Isolating mechanism http://animals.about.com/od/i/g/isolatingmechan.htm last visited 10-12-2010
  • Bio Ed Online (2010) Mechanical isolation http://www.bioedonline.org/slides/slide01.cfm?q=%22mechanical+isolation%22&dpg=1 last visited 10-12-2010.
  • Geology Rocks (2009) Kinds of isolation http://www.geologyrocks.co.uk/tutorials/isolation_new_species last visited 10-12-2010.
  • Nicholas, H.B. et al. (2007) Evolution (1st ed.) John Inglis
  • Nicksnowden (n.d) classification, selection and evolution http://www.nicksnowden.net/Other_pages/545_Classification_Selection_and_Evolution.pdf last visited 10-12-2010.
  • Scott, F. and John, C.H. (2007) Evolutionary analysis (4th ed.) Pearson Education.
For cells to stay alive and perform their biological functions, materials such as food, oxygen, ions and waste products must be transported in and out of the cells. This occurs through a permeable membrane that regulates the size and nature of substances that enter or leave the cell (Julian, et al, 2006). Due to concentration gradient in cells, these molecules and ions move down or against the concentration gradient depending on weather they are passively transported; which requires no input of energy or they are actively transported; requiring input of energy provided by adenosine triphosphate (ATP) in the mitochondria respectively (Lauralee, 2006). Lauralee further stated that some of these molecules are too large enough to pass through the plasma membrane and so require special protein structures in the membrane to be transported (facilitated diffusion and active transport) while some form vesicles and get fused with the cell membrane (bulk transport). Therefore, the need for cells to develop various mechanisms for transporting these materials across the plasma membrane. Lauralee again, states that these mechanisms are lipid diffusion, osmosis, facilitated diffusion, active transport and bulk transport (endocytosis and exocytosis). This essay will feature on how these processes work and some of the life examples involved.

Linda (2008) explains that diffusion is a form of passive transport involving the net movement of molecule from an area of high concentration to an area of lower concentration. Linda further added that the process does not require energy input (rather, the molecules are moved by their kinetic energy) as molecules move down their concentration gradient. Austin College (n.d) further added that although molecules move down their concentration gradient, factors such as surface area, difference in concentration, distance of molecules from the membrane affect the rate of diffusion. Richard and Jean (1996) give example of diffusion to occur when carbon(IV)oxide and oxygen are exchanged in the alveoli of the lung where they move down their concentration gradient with the carbon(IV)oxide diffusing out of the blood and oxygen diffusing into the blood. Osmosis is a special case of diffusion involving the net movement of water from a region of high water potential to a region of lower water potential through a semi-permeable membrane (Lauralee, 2006). Like diffusion, it does not require energy as the water moves down the concentration gradient. Glenn and Susan (2002) suggest that this mechanism takes place in a hypotonic and hypertonic solution until equilibrium is reached (isotonic solution). Osmosis, for example occurs in the uptake of water from the soil by the root hairs due to high mineral concentration in the roots of plants (Millersville University, 2010).

  Another type of passive transport across membrane is facilitated diffusion, where large and polar molecules and ions such as glucose and chloride ions are transported from area of high concentration to area of lower concentration through special openings called carrier and channel proteins in the cell membrane (Vivo Education, 1997). Again, no energy is expended. Vivo Education further added that Channel proteins may be gated whereas carrier protein changes shape as the material is being transported across. For example, glucose is bind to a carrier protein called permease which changes shapes as it transports the glucose across into the plastid to be stored as starch (College of West Anglia, n.d). Another example is seen in the transport of sodium ion into the neuron through gated ion channels (National Yang-Ming University, 2001).

  Some larger molecules and ions cannot pass through the plasma membrane and move against the concentration gradient from an area of low concentration to an area of higher concentration across membrane using special protein structures called carrier proteins (membrane pump). This is referred to as active transport as it uses energy in the form of ATP to transport larger molecules and ions against their concentration gradient (Lauralee, 2006). For example, iodine is actively transported in the blood to the 99% stored iodine in the thyroid gland (Lauralee, 2006). Carl Albert State College (2005) adds that the transport occurs in transport proteins called uniport, antiport and symport. It further states that in uniport, a single molecule is transported only in one direction; antiport transports two molecules across membrane in opposite directions while symport transports two different molecules across membranes using energy from ATP. For example, three sodium ions is actively pumped out of the cell using a phosphate from ATP and two potassium ions are subsequently pumped into the cell, a process also referred to as sodium potassium ions pump (Lauralee, 2006).

  Molecules such as proteins, polysaccharides, nucleic acids, hormones and enzymes are too large enough to pass through the plasma membrane and so are transported in tiny membrane bound-sac called vesicles which fuse with the plasma membrane and get molecules transported across (Thomas, 2002). This process of transporting larger substances in vesicles is called bulk transport and it involves two processes-endocytosis and exocytosis against a concentration gradient and so energy from ATP is used (Mary, 2008). Endocytosis involves the transport of materials in vesicles outside the cell, where the vesicle fuses with the cell membrane and the molecule gets transported out of the cell (Daniel, 2005). Daniel cites an example where protein hormones in the endocrine glands form vesicles which fuse with the plasma membrane and are then released into the extracellular fluid. Endocytosis involves the intake of materials into the cell which maybe in the form of fluid-pinocytosis or in solid form-phagocytosis (Thomas, 2002). Example of phagocytosis occurs when phagocytes invaginate microbes, which are then acted upon by enzymes and get destroyed in the vacuole (Mary 2008). pinocytosis occurs when some useful substances are taken by cells lining the blood capillaries (Thomas, 2002). Thomas also suggested a third form of endocytosis as carrier mediated endocytosis where certain materials are transported into the cell by receptors giving examples to occur when iron is carried by the transferrin protein carrier in the blood.

  In conclusion, substances such as carbon (IV) oxide, oxygen, glucose, proteins, and ions are transported between cells and their environment down or against their concentration or electrochemical gradients. Some of these substances are non polar such as carbon(IV)oxide, oxygen and urea while some are polar and too large enough to freely pass and so require special proteins in the membrane for transport. Some move against their concentration gradient requiring energy often provided by ATP from aerobic respiration in the mitochondria. All these are necessary for cellular activities to take place. Therefore, cells evolve different types of transport mechanisms to ingest materials and to get rid of waste products from the body. This is necessary to sustain the life of all living organisms.

  LIST OF REFERENCES

  • Austin College (n.d) Diffusion http://www.austincc.edu/~emeyerth/diffuse2.htm Last visited: 18-02-2011.
  • Carl Albert State College (2005) Membrane Transport http://www.carlalbert.edu/nmaxwell/Physiology/videos/plasma%20membrane%20animation.swf Last visited: 18-02-2011.
  • College of West Anglia (n.d) Transport Mechanisms in Cells http://intranet.col-westanglia.ac.uk/storage/resources_net/curriculum-press/BioFactSheets/Bio%20Factsheets/116_TRANS_CEL.pdf Last visited: 18-02-2011.
  • Daniel, D. (2005) Human Biology (5th ed.) Jones and Barlett Publishers, London.
  • Glenn, T. and Susan, T. (2002) Essential AS Biology Nelson Thornes Ltd, UK.
  • Julian, S., et al (2006) Concepts in Medical Physiology Lippincott Williams and Wilkins, Baltimore.
  • Lauralee, S. (2006) Fundamentals Of Physiology Thomson Brooks/Cole, USA.
  • Linda, B. (2008) Introductory Botany (2nd ed.) Thomson Brooks/Cole, USA.
  • Mary, J. (2008) Biology 1 For OCR Cambridge University Press, United Kingdom.
  • Millersville University (2010) Water Relation, Osmosis and Transpiration http://herbarium.millersville.edu/class-web/botany2010/lab11-water.pdf Last visited: 18-02-2011.
  • National Yang-Ming University (2001) Membrane Structures And Functions http://www.dls.ym.edu.tw/bio1/100206-1.pdf Last visited: 18-02-2011.
  • Richard, F. and Jean, M. (1996) Biology Heinemann Educational Publishers, Oxford.
  • Thomas, M. (2002) Cell Membrane http://www.sp.uconn.edu/~bi107vc/fa02/terry/membranes.html Last visited: 18-02-2011
  • Vivo Education (1997) Facilitated Diffusion http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/diffusion_f.html Last visited: 18-02-2011.

Aim:

The aim of the field trip was to determine the abiotic and biotic factors responsible for the distribution of organisms on the rocky shore at culler coat. It was also aimed at finding out the type of species that live in each of the shore zone and the factors responsible for their distribution on the rocky shore.

Safety:

Pairs of wellington boats were worn from the start to the end of the field trip. This was necessary to avoid the feet from getting cold. Hand grooves and sweaters were worn to cover the body, preventing the body from catching extreme cold of the sea. Again, care was taken when walking on the rock to avoid slippery which may lead to sustaining wounds or broken bones on the body. Again, hat was worn to conserve heat within the body system. During the field trip, waves from the sea were kept at careful observance to avoid been overwhelmed by the force. Finally, some of the sea species such as crabs were handled with care to avoid being bite off by them.

Equipment.

  • A Tape (which formed the transect line)
  • Quadrat (100 squares)
  • Wash bucket
  • Writing material to include a clip board and pen.

Methods:

Firstly, the area to be surveyed was mapped and divided into stations 1, 2, 3, and 4. This was necessary so as to study all the species in the low tide of the sea shore. Secondly, at station 1, the quadrat was thrown randomly on the rocky surfaces and the number of organisms present was counted and some estimated as percentage cover. The quadrat was repeated for another three times so as to cover all the species but at random in station 1. Some of the species found in station 1 were spiral weeds, gut weeds and porphora.

Thirdly, at station 2, the transect line was laid across the rocky surface of the surveyed area. Then the quadrat was randomly placed horizontally along the edge of the transect line. This was done by maintaining a specific distance along the transect line. This method of random sampling is called belt transect. The species covered by the quadrat was then counted or estimated and recorded. Some of the species the station were estimated as percentage cover since it was not possible to count the individual species involved. Examples of these species were barnacles and black tar lichens. This was done by counting the number of squares in the quadrat that was roughly covered by these species which represented the percentage cover. This procedure was repeated along the transect line with three quadrats at random. The repetition was necessary so as to determine an estimate of the different species studied along the transect line. It was also necessary so as to get other species have an equal chance of occurrence. However, some of the species were absent in some surveyed area along the quadrat. Some of the species surveyed and studied in station 2 are common limpets, black tar lichens and barnacles.

The method and procedures above was repeated for station 4. Station 4 was close to the sea than other stations and so rock pools were avoided when placing the quadrat. Some of the species studied in station 4 were common limpets, barnacles, toothed wrack, pepper dulse, oarweeds and dulse. However, at station 3, the quadrat was placed vertically along the rock surface and the species present were recorded either by counting such as limpets or by percentage cover such as pepper dulse, barnacles, false Irish moss or toothed wrack. It was ensured that four quadrats were also covered. Finally, the population of the species in each station were summed up and the average calculated and recorded against the species

Results:

Observations: During the experiment, it was observed that species were not distributed normally on the rocky shore. Some areas were concentrated with a particular species or with small population with some species totally absent in some areas. It was also observed that as the day goes by, the sea was fast approaching the rocky surfaces with high waves. This was suggested to be caused by tidal movement. The factors responsible for these partial distributions of species shall be discussed in the discussion section.

Result Table 1

Table1: Table showing the Overall Result of the distribution of organisms on the rocky shore at culler coat on Wednesday, March 10th, 2011.

RESULT TABLE 2

Table 2: Table showing the Average Result of the distribution of organisms on the rocky shore at culler coat on Wednesday, March 10th, 2011. Fig.1: Kite diagram showing the distribution of toothed wrack and barnacles at culler coat on March 10, 2011

Discussions:

The result shows that organisms are not normally distributed on the rocky shore. At a place, they appear dense, while at other stations, they appear dispersed or totally absent. This is proven above. Some of the species are calculated as a percentage cover of the area under survey. For example, from table 2, the population of common limpets changes from zero to 15, 28 and 10 at each of the of the different stations while in station 1, common limpets and black tar lichens were totally absent. Spiral weeds, gut weeds and porphora were present with population numbers of 26, 66 and 21 respectively but were absent in other stations. This shows that there are factors responsible for the distribution of organisms on the rocky shore and these factors affect the location, type and population of each species under survey.

The barnacles and toothed wrack are to be discussed in relation to these factors affecting their distribution. The kite diagram above shows that toothed wrack is absent in both stations 1 and 2 while there was an increase in the percentage cover of the toothed wrack in station 3 which further increases up to station 4. Again, the kite diagram of the barnacle sp. shows that there was no barnacle at station 1 but there was an increase in station 2 which decreases progressively from station 3 up to station 4. This shows that station 2 recorded the highest number of barnacles. The shapes of the two kite diagrams show that the species were unevenly distributed in each of the stations. These factors affecting the distribution of organisms on rocky shore are classified into biotic and abiotic factors. Barrette, et al (2006) enumerates some of the abiotic factors as desiccation, temperature, wave action, light intensity, salinity, turbidity, pollution turbulence, aspect, slope, exposure, oxygen level and presence of rock pools. Barrette also suggests some of the biotic factors to include competition, food and feeding, predation and colonisation.

Barnacle sp. Such as chthalamus stellatus and semibalanus balanoides (David and Peter, n.d) combat the problem of desiccation, that is dryness resulting from absence of water by the possession of an exoskeletons which prevents them from drying up while toothed wrack, fucus serratus found on the lower shore is intolerant of desiccation, with only its fronds being dried up at low tides (Barrett, et al, 2006). Wave actions, that is, the force produce from tidal movement of the water also influence the location of barnacle sp. and fucus serratus. Barnacles prevent themselves from being washed away by attaching themselves firmly to rocky surfaces; however, fucus serratus are intolerant of heavy wave actions due to the possession of flexible fronds (Barrett, et al, 2006). Again, the exoskeletons of barnacle sp. protect them when the tide is out against temperature, although the temperature remains constant (5-150C) and so are buffered against large temperature change while fucus serratus has fronds that are larger with fewer branches which protect them and so are intolerant of temperature change (Barrett, et al, 2006). The distributions of barnacle sp. are not much affected by light but this is predominant in toothed wrack and so has pigment called fucoxanthin which absorbs the light that passes through the water (Barrett, et al, 2006).

Competition also affects the distribution of fucus serratus and barnacle sp. This competition may be for food, space, and mate and may be inter-specific or intra-specific depending on the species of organisms involved. For example, toothed wrack competes for space with sugar kelp, tangled kelp and coiled tube worm spirobis on the lower shore on rocks (Barrett, et al, 2006). This competition may at times be in favour of one species thereby affecting the distribution of the other species. Again, tidal movement affects the availability of food for barnacles. This is because they only feed when immersed in water. Predation also affects the distribution of species. For examples, barnacles are prey to dog whelks while fucuc serratus are eaten by periwinkle while both barnacles and toothed wrack feed on planktons (Barrett, et al, 2006). Therefore, if one species should out-compete the other, this will affect the distribution of both species.

The method of random sampling has been used in this survey. This is a sampling technique that involves the selection of a specific area to study organisms from a larger population with each species having an equal chance of occurrence which reduces bias (Easton and McColl, n.d). This was ensured in the selection of these species by repeating the quadrat along the transect line so as to get all species involved. The experiment could be improved by arranging for earlier arrival on the shore to carry out the experiment. This is to avoid being disturbed by tidal fluctuations. The experiment could also be improved by avoiding rock pool where it exists and also by avoiding been bias in the course of throwing the quadrat along the transect line. Again, the experiment could have been improved by ensuring that only one person was involved with the counting and estimation of the species so as to be consistent with the results and avoid personal perspectives and bias in the final result.

Conclusion:

It could be concluded that the distribution of organisms on the rocky shore are influenced by factors such as temperature, desiccation, tidal movement (wave action), light intensity, availability of food, and competition for space among others. Organisms are able to confront these factors by developing specialised structures or behaviour. It has also been found that the absence of some of these factors have effects on the population, type and location of species on the rocky shore. A large population of species shows that a prevailing factor is favourable to the existence of such species on the rocky shore. It has also been found that out of all these factors, tidal movement determines the abundance of organisms at each zone in the rocky shore with more species on the lower shore due to the availability of food washed down by the tides and other favourable factors.

LIST OF REFERENCES.

  • Barrett, B. et al. (2006) Biotic And Abiotic Factors Affecting The Location And Adaptation Of Organisms http://biology.slss.ie/resources/seashoreposters18.pdf Last visited: 18-03-2011.
  • David, P. and Peter, R. (n.d) Barnacles http://bio.research.ucsc.edu/people/carr/Raimondi%20Reprints/Barnacle%20chapter%20proofs.pdf Last visited: 18-03-2011.
  • Easton, V. and McColl, J. (n.d) Statistical Glossary: Sampling http://www.stats.gla.ac.uk/steps/glossary/sampling.html Last visited: 18-03-2011

ANSWERS TO QUESTIONS

  1. What reaction does catalase catalyse?
Catalase catalyses the reaction of the decomposition of hydrogen peroxide to water and oxygen as it speeds up the reaction rate.
  1. What control did you/should you have used for this experiment?
The control should have been done by measuring the same volume of water as that of the catalase and pour in different boiling tube. This will then be placed in the water bath containing the different temperatures and one kept under the room temperature.  After the 10 minutes, they should have been removed and used to measure the time taken for the filter paper disc to rise up in the hydrogen peroxide.  It will be discovered that the filter paper disc will not rise up or take a few minute to rise up if at all.
  1. How does temperature affect the activity of catalase?
Increase in temperature increases the activity of catalase up to the optimum temperature.  This is because the molecules have sufficient energy to overcome the activation energy and due to increase in kinetic energy of the enzyme-substrate complex as they collide more easily as temperature increases.  However, above the optimum temperature, the activity of catalase decreases as the protein in it, is denatured and the lost of shape by the active site.  The graph above shows this observation.  From the graph, the rate of catalase activity increases up to 300C and above this temperature, it rate of activity decreases as the hydrogen bond in the protein structure are being disrupted.
  1. How do high and low temperatures affect protein structure?
High temperature increases the kinetic energy of protein and causes the protein molecule to vibrate so rapidly that the hydrogen bond in the protein structure is broken.  It also disrupts the non-hydrophobic interactions of the protein.  These actions change the tertiary (3D) structure of the protein and so it is denatured.  This affects the metabolic functions of the protein.  Low temperature also affects the efficiency of some proteins.  They decrease the metabolic activity of proteins and also change the shape of some proteins in rare cases of extreme low temperature.
  1. How would you adapt this experiment to investigate the effect of enzyme concentration on the rate of reaction?
The experiment can be adapted to investigate the effect of enzyme concentration on the rate of reaction by for example, using different concentrations of the enzyme-catalase and keeping the temperature at an optimum range and same for all the different concentrations of the catalase and then remove after sometimes and use them to measure the reaction rate.  It would be observed that the more the concentration, the more the rate of reaction of the enzyme with the substrate.

EXPERIMENTAL DATA

 

Aim

The aim of the experiment was to determine the effects of different temperatures and chemicals and frozen ice on the plasma membrane.

Safety

Safety ensures life continuity and so it is important to apply safety precautions during any laboratory practical.  During this experiment, lab coat was worn all through to avoid the purple beetroot colour from staining clothes, which is always hard to remove.  Gloves were also put on to avoid the beetroot pigment from staining the hands.  The hot water in the water baths was not touched with the bare hands to check the hotness rather it was read from the bath display.  This was to ensure that the test-tubes containing the beetroots were placed in the correct baths.  The inside of the colorimeter was checked to ensure it was free of solution that may have been spilled by other groups to ensure the accuracy of the reading.  When cutting the beetroot, the cork borer was used and placed directly on the white tile surface and not on the palms to avoid cuts and wounds.  The stopwatch was checked always to avoid missing the time frame for each test-tube.

Methods

Firstly, the beetroot was bored through using the cork borer.  Then the cylindrical beetroot portion was chopped into nine pieces of 1cm long each using a knife, discarding the skin.  10cm of distilled water was measured using the measuring cylinder and poured into three test tubes.  Then three chopped pieces of beetroot were put into each test-tube using the tweezers and placed in the rack for 30 minutes to leak out the beetroot pigment.  These serve as the control, and were labelled control 1, 2, and 3. Secondly, other six chopped pieces of beetroot were placed in six different test tubes.  To the first test-tube was added an industrial detergent and labelled ``detergent’’.  To the second test-tube was added ethanol and labelled ``ethanol’’.  Then the two test-tube were placed in the rack.  Other four test-tubes were each placed in ice, in 300C, 500C, and 700C respectively.  They were each labelled frozen ice, 300C, 500C, and 700C respectively to ensure accuracy and avoid mixing up the test-tubes.  All the six test-tubes were left undisturbed for 10 minutes but at exactly the very time they were prepared. After the 10 minutes was over, the beetroot samples in detergent and ethanol were removed and rinsed with distilled water to wash off all the excess pigment released from the beetroot and the solution of ethanol and detergent for result accuracy.  The test-tubes in the water baths and frozen ice were also removed at the 10 minutes time, but were not rinsed.  Then 10ml of distilled water was measured and added to each of the beetroot in each of the test-tubes and left undisturbed for 30 minutes.  After the 30 minutes was over, the beetroot samples were removed from each test-tube (both the control ant the experiment) using the spatula.  The beetroot samples were then got rid of.  Then the coloured solution in each nine test tubes was mixed properly. Finally, each of the coloured pigments were each poured into a small plastic container called cuvette and then placed inside the hole in the colorimeter ensuring that the solution does not spill into the hole.  Then the button was pressed to send beam of light through the solution.  The absorbent unit for each solution was then recorded against each solution on a tabular sheet.  During the experiment, the room temperature was 150C.

Results

Observations: several changes were observed during the experiment.  After the beetroot samples were placed in the 10ml of water, purple pigment gradually spread out of the beetroot and diffuse throughout the solution.  This shows that the beetroot contains a pigment in the cell membrane that is responsible for its pigmentation.  The degree of pigmentation in the control solution was less than that in the experiment.  Again, there was no distinctive colour change of the detergent in the in the test tube, though a dark green colour was observed around the beetroot.  The viscosity of the detergent may have affected the spread of the pigment.  It was also observed that the more the pigmentation, the less the less the value of the result.  This shows that degree of pigmentation has effects on the transmission of light beams.

CLASS DATA

Label of Test tube solutionColorimeter’s absorbent unit(ABS)
Ethanol   0.4050
Industrial detergent 0.0500
Frozen ice0.0100
Temperature of 30OC    0.0275
Temperature of 50oC    0.0450
Temperature of 70OC    0.2650

Discussions

The result shows that temperature has effect on the plasma membrane of the beetroot.  From the result, as the temperature increases the value of the absorbent unit increases, showing that more pigment is leaked out of the vacuole of the cell of the beetroot.  Ethanol and detergent also have effects on the plasma membrane of the beetroot.  The result is accurate as it shows a gradation in the value of the ABS as the temperature increases. Possible errors may arise from the colorimeter.  If the colorimeter contains some spilled solution from the cuvette before the next cuvette was placed, this will affect the reading of the calorimeter.  Errors may also result from adding more or less water to the beetroot in the test tube.  Therefore, care must be taken to focus on the meniscus of water in the measuring cylinder.  Finally, if the solution was not mixed up before transferring to the cuvette, this will cause an error in the reading of the colorimeter. Therefore, for accuracy of result, the hole in the colorimeter should be checked to be free of any solution.  A replicate should always be done to compare the result. Beetroot contains some purple pigment known as betacyanin and a yellow one known as betaxanthin.  Both are collectively known as betalins.  It gives the beetroot its characteristic colour and is present in the tonoplast, which surround the cell vacuole.  There is always a popular misconception of the saying that cyathocyanin is responsible for the pigment in beetroots, but this is untrue.  (www.selfsufficientish.com, 2008).  Temperature also has effects on the plasma membrane.  The more the temperature, the more the dye that leak out of the vacuole of the cell, which consequently denature the protein in the plasma membrane.  Fat is contained in the lipid part of the cell membrane, which is emulsified by detergents.  Cell membranes are made up of phospholipids bilayers.  The detergent’s hydrophilic tail repels the individual phospholipid and so disrupts the structure of the plasma membrane.  This causes more dyes to leak out of the tonoplast (www.123helpme.com, 2010).  Ethanol also has effect on the plasma membrane.  A higher concentration of ethanol will increase the permeability of the membrane.  This will cause more dyes to diffuse out of the membrane due to the disruption of the lipid part of the plasma membrane.  It also denatures protein at higher concentration.  (www.studyzone.com, 2005).

Conclusion

The result shows that different temperatures have effects on the plasma membrane.  It also shows that certain chemicals like detergent and ethanol have effects on the permeability of the cell membrane.

References

Aim

The aim of the experiment was to investigate the different concentration of sucrose solution on the mass of the potato and to determine the concentration of the potato used.

Safety

Lab coat was worn throughout the experiment to avoid any spill from direct skin contact.  Carefulness was observed in peeling and cork-boring the potato to avoid any cut or damage on the skin.

Equipments

  • Boiling tubes
  • Boiling tube rack
  • Chopping board
  • Vegetable peeler
  • Potatoes
  • Cork borer
  • Knife
  • Filter paper
  • Balances
  • Distilled water
  • Sucrose solutions: 0.2 moldm-3, 0.4 moldm-3, 0.6 moldm-3 , 0.8 moldm-3 ,1 moldm-3 

Methods

Firstly, the potato was peeled off using a knife.  Then the cork borer was used to bore holes through the peeled potato from where cylindrical portions of potatoes were produced.  The cylindrical portions were measured into equal lengths of 1cm using a scale rule and then carefully cut out into eleven pieces.  Other left over of the potato were discarded.  The masses of each of the eleven portions were measured with a lab scale and recorded.   During the measurement, air was not allowed to circulate around the lab scale as it obstructs the mass of the specimen to be measured on a lab scale. Ten of these 1cm long potato pieces were placed in different boiling tubes already labelled with the different concentrations of the sucrose solution.  Then the masses of each potato portion were labelled on each specific boiling tube for accuracy and identity.  After this, the different sucrose solutions to be used were each poured halfway into five different boiling tubes and the replicates produced for the other five boiling tubes with the same solutions taking note of the labelling.  Then the potato was left for one hour undisturbed.  The remaining potato was placed in a boiling tube and had water filled halfway of the tube.  This served as the control of the experiment. After the one hour has elapsed, the potato portions were removed from the solutions with a spatula and blot gently with filter paper to remove the surplus liquid.  This was done to avoid additional or anomalous mass on the potato to be re-weighed.  Then each of the pieces was re-weighed and the average calculated for each replicate.  The average for each replicate of the masses before the experiment was also calculated and all the data were tabulated with the corresponding sucrose solutions. Finally, the change in mass was calculated for each ‘before’ and ‘after’ mass.  Then a graph was plotted for the percentage change against the molarity of the sucrose solutions.

Results

Observations: During the start of the experiment, it was observed that all the potato settled at the base of the boiling tube in the sucrose solutions and the control (distilled water).  But later after about 45 minutes, the potatoes in the 0.8 mol/dm3 and 1mol/dm3 were seen to rise up the tube to nearly the surface of the solution.  This was thought to have been due to the phenomena of osmosis where water moved out of the potato through the semi-permeable membrane of its cell to the solution of sucrose to create equilibrium in concentration and by so doing reducing the mass of the potato as observed in the data below. Again, there was a gradual change in the colour of the solutions from colourless to pale-yellow solution starting from the area within the potato outwards.  This was thought to be as a result of the diffusion of the potato pigment into the solution.  It was also observed that there was a change in the mass of the potato after the experiment.  There was also some minute change in the level of the solution in the boiling tube and in the control, caused by the net movement of water molecules.
GROUP DATA
TimeSucrose solution(mol/dm3)ReplicatesAverage(g)
Portion1(g)Portion2(g)
Before experiment0.00(H2O)0.900.910.91
0.200.860.880.87
0.400.920.910.92
0.600.980.980.98
0.800.870.990.93
1.000.960.990.98
After  experiment0.001.001.001.00
0.200.920.910.92
0.400.940.910.93
0.600.930.900.92
0.800.790.890.84
1.000.830.820.83
 
AVERAGE GROUP DATA
Molarity(mol/dm3)0.000.200.400.600.801.00
Average mass before (g)0.910.870.920.980.930.98
Average mass after (g)1.000.920.930.920.840.83
Change in mass (%)+9.9+5.8+1.1-6.0-9.7-15.3

Discussions

Analysis from the result shows that concentration gradient affects the net movement of water molecules across the semi-permeable membrane of the potato.  This could be seen in the change in average mass of the potato as shown in the table.  Different concentration of sucrose solutions increase or decrease the mass of the potato due to the net movement of water molecules into and out of the potato.  From the average group data, for example, from 0.00mol/dm3 (distilled water: control) to 0.40mol/dm3, it was observed that there was a net movement of water into the potato from the surrounding environment (endocytosis, hypotonic solution) which shows that the concentration inside the cell of the potato was more than the surrounding solution.  This increased the mass of the potato when re-weighed as shown above.  On the other hand, from 0.60mol/dm3 to 1mol/dm3, it was observed that there was a significant net movement of water molecules out of the potato (exocytosis, hypertonic solution) which shows that the concentration of the surrounding medium was more than the inside of the cell.  This reduced the mass of the potato when re-weighed as shown above. These observable changes in mass and net movement of water in and out of the potato and/or the sucrose solutions were due to difference in solute concentration of the two medium.  The positive percentages show that water move into the cell while the positive percentages show that water move out of the cell and so reduced the mass progressively.  This caused the potato in the 0.80mol/dm3 and 1mol/dm3 to rise up the tube. The graph shows that as the molarity of the sucrose solution increases, there was a decrease in the mass of the potato due to net movement of water through a semi-permeable membrane.  From the graph, the result shows the molar concentration of the potato core to be approximately 0.44mol/dm3.  This figure is significant because it shows a transition point at 0.00% between water intake and out of the potato.  This can be proven from the average group data as shown by 0.40mol/dm3 and 0.60mol/dm3 mass change (from being hypotonic to hypertonic solution).  The 0.44mol/dm3 of the potato signifies that should the potato had been put into a 0.44mol/dm3 sucrose solution; there will be no movement of water molecules due to equilibrium of solute concentration (isotonic solution). The straight line on the graph could not pass through all the points on the graph.  This may have been due to some minute errors during the experiment, or in calculation and measurement of masses on the lab scale and/or the time allowed for equilibrium to be reached.  To reduce these errors, efforts should be focused on the experiment especially during measurement of masses.  Again, more time should be given for the experiment to get to equilibrium and carefulness during calculation and plotting graphs. The result shows a special phenomena or case of diffusion called osmosis.  This could be defined as the net or overall movement of water molecules through a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (Barry, H., pg. 239, 1993).  From the experiment, there was the application of osmosis.

References

  • Barry, H. (1993) A Textbook Of Science For Health Professions (2nd) Nelson Thomes Ltd, United Kingdom.

Aim

To produce a solution of 0.1M

 Safety measures

  • I made sure I was on lab-coat. This was to avoid direct skin contact with the Potassium Hydrogen Phthalate (KHP) solution if it were to split.
  • I wore safety spectacles or goggle to avoid the solution splitting into my eyes.
  • I ensured my hands were covered with gloves to avoid contact with the solution.
  • I ensured that the KHP sample was measured correctly as 5g to avoid any change in the concentration of the solution.
  • I ensured there was no air interference to avoid changes in mass during the measurement by measuring it in an enclosed place.
  • I ensured to measure the required 50cm3 by constantly checking the water meniscus in the beaker.
  • I stirred the solution in the beaker constantly for proper dissolution
  • I ensured the beaker was rinsed with distilled water to avoid any left-over during transfer into the volumetric flask.
  • I ensured the flask was shaken twenty times as instructed
  • I ensured the table surface was dried with racks after the practical to avoid any effect on the skin.
  • I labelled the solution with KHP, my name and date to avoid identification problem
  • And finally, I disposed of the gloves and washed my hands with disinfectants to keep my hands free of chemical

    Equipment

  • Tray,
  • Volumetric flask,
  • Watch glass,
  • Water bottle containing distilled water,
  • 250cm3 beaker,
  • Bottle containing Potassium Hydrogen Phthalate,
  • Dropper pipette,
  • Electronic lab scale,
  • Filter funnel,
  • Spatula and
  • Stirrer

Method

The watch glass was first weighed on the electronic lab scale and record made.  Then solid KHP was placed drop by drop with the spatula and the mass was recorded.  Then the mass was subtracted from the mass of the watch glass to give 5g- the required mass of solid KHP. The watch glass was then taken off the scale.

Distilled water measuring 50cm3 as read from the beaker`s scale was poured into the 250cm3 beaker.  The 5g was re-weighed for accuracy and transferred into the beaker and stirred vigorously. Excess water was added and stirred continuously to dissolve the solid KHP.

After all the sample has dissolved, it was transferred into the volumetric flask using the filter funnel.  The beaker was rinsed with distilled water and added to the solution in the volumetric flask.  Water was further added until the water meniscus was roughly 1cm above the flask`s neck.  Then the stopper was inserted and the flask shook vigorously.

The stopper was removed and water added again to the solution drop by drop with the dropper pipette until the water reached the marked portion of the flask.  Then the stopper was replaced and the flask was shaken for twenty consecutive times for accurate dissolution.

Finally, the prepared standard solution was labelled with “KHP solution”, my name partner`s name with the date also attached.

Result

Mass of KHP and watch glass………………………………………………………………22.090g Mass of watch glass after transfer…………………………………………….………..17.090g  

Discussion

If some solid KHP was spilled during the transfer from the beaker into the volumetric flask, this would have affected the concentration of the solution by decreasing it, but I avoided such a mistake.  Also, if during the experiment, some samples of KHP remained in the watch glass, this would have decrease the concentration of the solution.  In a condition where enough water was not added, the concentration of the solution would have increased above the normal.  All these would have significant effects on any further calculations.

My results show a close value with the required concentration of 0.01M of KHP with only a slight difference of 0.002M which is slightly insignificant.  The 0.098M can be approximated to 0.01M.  Therefore, there was a little accuracy in my results.

KHP is a good primary standard for many useful reasons as a chemical substance.  It is a passive solid compound as it does not easily react with air or Oxygen.  Its weight or high molar mass also make it a good primary standard.

KHP  is an important primary standard chemical due to its common nature, high purity, low affinity for Oxygen; moisture or carbon(IV)oxide, high molecular mass and its solubility in water(RICCA COMPANY, 2008)

Also, KHP is useful in titration because it can dissociate into its respective ions easily; producing hydroxonium ion, H3O+ with a steady PH value.  In solution, KHP splits completely giving the Potassium ion, K+ and Hydrogen Phthalate ion, HP_ being weak; it reacts reversibly with water yielding a hydroxonium ions and phthalate ions (Wikipedia, 2010)



Conclusion

A standard primary solution of KHP can be produced in the laboratory.  I have able to prepare a standard solution of 0.10M of KHP.

References

For a reaction to occur, particles must first collide and must have energy greater than the activation energy to overcome the energy barrier and break bonds.  The reacting particles must also be in the right direction.  Therefore, the rate of reaction is the change in concentration over time.  Several factors such as
  • Surface area,
  • Concentration,
  • Temperature, and
  • Catalyst
affect the rate a chemical reaction takes place.  This essay will feature the last three factors with some experimental data to support the effect of these factors.
CONCENTRATION
A change in concentration affects the rate of a reaction.  An increase or decrease affects the reaction rate by either increasing or decreasing the product formation respectively.  Therefore, increasing the concentration increases the rate of reaction and vice versa.  As the concentration of the reactant increases, there is greater chance of collision between particles and therefore, more bonds are broken.  However, the concentration decreases as the reaction proceeds.  For example, from the experiment conducted in the lab between KIO3 and starch; a higher concentration of KIO3 yielded products (when the solution turned dark blue) in 57 seconds and when half the concentration was used, the reaction time was 104 seconds.
TEMPERATURE
An increase or decrease in temperature affects the rate of a chemical reaction by increasing or decreasing it respectively.  As the temperature increases, particles gain more kinetic energy and therefore, more collisions between reacting particles.  As a result, the activation energy is overcome and so reaction happens at a much faster rate. For example, from the reaction between KIO3 and starch, when the reaction was carried out under normal room temperature, the reaction time for a dark blue colour to show up was 57 seconds, but at a higher temperature of 350C, the reaction happened quicker in just 45 seconds.  Therefore, an increase in temperature increases the reaction rate.
CATALYST
A catalyst is a substance alters the rate of a reaction by speeding it up, but itself remains chemically unchanged at the end of the reaction.  A catalyst increases the rate of a reaction by lowering the activation energy of the reaction.  Therefore, a catalyst reduces the time required for a reaction to take place.  A non-catalysed reaction happens at a much lower rate than a catalysed reaction.  Again, catalysts are specific in the reaction they catalyse.  Moreover, a catalyst could be heterogeneous or homogeneous depending on the state of the catalyst in the reaction system.  For example, in a reaction between iron (III) nitrate solution and sodium thiosulphate, it took 47 seconds for the reaction to take place when no catalyst was used.  When iron (II) catalyst was used, it took 44 seconds and when CUSO4 was used, it took only 7 seconds.  This shows that a specific catalyst will only catalyse a specific reaction and not all catalysts work for all types of reactions.
RESULTS ON RATES OF REACTIONS EXPERIMENT
SolutionTime (mins)
KIO3  +  Starch00:57
Warmed KIO3  +  Starch00:45
½ Conc. KIO3  +  Starch01:45
RESULTS ON CATALYSIS EXPERIMENT
No catalystCUSO4FeSO4
Time (s)47744

INTRODUCTION

Group 1 metal are Li, Na, K, Cs, Rb, and Fr, having one electron in their outer most shells.  They are very reactive with water yielding an alkali and a Hydrogen gas; therefore, are called alkali metals.  They react easily with oxygen and vapour on exposure to the atmosphere and so tarnish easily.  Lithium is coated black while potassium and sodium are grey in appearance.  When cut, their surfaces shows a metallic lustre-very shiny, but tarnish easily and therefore, are stored in paraffin oil in a bottle container placed inside another bottle surrounded by a granulated substance called vermiculite to absorb water.

REACTIVITY TREND

The reactivity of alkali metals with water increases down the group with Lithium being the least and Francium-the highest.  This is so because, down the group, the nuclear charge increases as protons are being added to the next energy level (number of shells increases down the group).  Therefore, shielding increases down the group due to the addition of electrons to each successive energy level.  This increases the atomic radii progressively down the group.  Electrons in the outer most shell therefore, experience less nuclear attraction from the nucleus and so are easily removed(oxidation), making them a good reducing agent.

OBSERVATIONS

When Li, a black coated solid is dropped in a water bath placed in a fume cupboard, the Li is seen to move randomly on the water surface producing a fizzy sound while it reacts with water.  Bubbles are observed on the water surface with effervescence and heat being given off-exothermic reaction.  The reaction of sodium with water occurred more vigorously than Li with water.  It reacts spontaneously with water producing an orange flame and a fizzy sound is heard as the hydrogen gas is being given off with large amount of heat produced.  Potassium reacts violently with water liberating Hydrogen gas with a lilac colour sparkling.  Its reaction is very explosive as compared to Na with more effervescence and heat given off.

Rubidium, Caesium and Francium are relatively much more reactive than other alkali metals with Fr being the highest and so they are not carried out in the Lab.  This is because they have a short half-life and react very explosively with water liberating Hydrogen gas and enormous heat and sparkling with Caesium having a violet explosion When universal indicator is added to the solution, its colour changes from green to purple indicating the presence of alkali solution.

Aim

The aim of the experiment was to synthesise, isolate, purify and identify a fruit flavouring ester called octyl acetate from the reaction between octan-1-ol and ethanoic acid under reflux. The identification was done through smell, colour change and infra-red spectroscopy.  

Safety

Glacial acetic acid (ethanoic acid) is poisonous if swallowed.  It is also irritating to the skin and eyes and can cause burns and ulcers. (Athabascau University, n.d). Therefore, proper care was taken by wearing lab coat and hand groves and equally, safety goggles. Sulphuric acid is very corrosive and therefore, can cause severe skin burn.  Octyl acetate poses health hazards such as eye and skin irritation, irritation of the digestive and respiratory tracts if ingested or inhaled respectively. (Athabascau University, n.d).  Diethyl ether is extremely flammable.  Sodium carbonate, although has no significant health hazards, contact with the eyes may cause mild irritation, redness and pain.  Magnesium sulphate may cause mild irritation to eyes, skin and respiratory tract (if inhaled).  The reactions involving glacial acetic acid was carried out in a fume cupboard to avoid inhaling the odour and skin contact.  Care was taken when using the ether to avoid contact with the skin.  Any chemical spill was cleaned immediately to avoid skin burn.  Most of the experiment was conducted in the fume cupboard to avoid inhalation of gases and any potential flame.  Care was taken when venting the funnel to avoid spills and pressure build up in the separating funnel when Na2CO3 was added.

EQUIPMENT

  • Alcohol (octan-1-ol)
  • Carboxylic acid (acetic acid)
  • Magnesium sulphate
  • Concentrated sulphuric acid
  • 5% Sodium carbonate
  • Diethyl ether
  • Silica gel as anti-pumping granule
  • 50ml and 250ml round bottomed flasks
  • 100ml and 250ml beakers
  • 250ml separating funnel
  • 2 Conical flasks
  • Spatula
  • Fluted filter paper
  • Distilled water
  • Reflux condenser
  • Pipette and measuring cylinders.

METHODS

The reaction was carried out in three phases.  Firstly, it was carried out in the fume cupboard where 10ml of acetic acid was measured into a 5oml round bottomed flask and then added to it, 10ml of octanol.  Few mass of anti-bumping granules was added to the mixture. Next, drops of concentrated sulphuric acid (approximately 1ml) was carefully added to the content of the flask and then swirled for proper mixture. The mixture was then heated under reflux in a water cooled condenser where the mantle was turned on to allow the flow of water through the tube.  This process was allowed for 10 minutes and thereafter, the mantle was turned off and the flask allowed to cool down. The cooling process was speed up by placing the flask in a 250ml beaker of crushed ice from where the mixture was transferred into a 100ml beaker containing approximately 25ml of crushed ice and then swirled to allow the ice melt completely.

Secondly, the mixture was transferred into a 250ml separating funnel. The content of the beaker was rinsed with a little diethyl ether.  Then 20ml of diethyl ether was further added to the solution in the separating funnel.  The solution was swirled and allowed to separate from where the lower aqueous layer was decanted off into the first conical flask.  Next, about 20ml of Na2CO3 solution was added to the remaining upper solution and then allowed for sometimes unstoppered until effervescence ceased. It was then covered and inverted several times and periodically unstoppered to allow the escape of CO2 and had the pressure reduced until gaseous evolution was complete.  Two layers were formed, which were separated as before.  The process above was again repeated to have all the solution free of acidic impurities.  Again, the already decanted upper layer containing the ester was poured into a second dry conical flask and had added to it, a hygroscopic substance called solid magnesium sulphate, one spatula at a time and had it swirled until all the MgSO4 formed clustered together in the solution.  This was done to dry the ester.  Then the solution was filtered into a 250ml round bottomed flask using a fluted filter paper.  The solvent was then removed under reduced pressure using a rotator evaporator to get rid of any possible starting material, reagent used and water.

Finally, the crude ester was poured into a 25ml round bottomed flask and then had it placed in a fume cupboard for distillation by heating using a 50ml capacity heating mantle with the boiling point of the ester noted.  Although, it was not boiled to dryness, a little residue was left in the distillation flask.  After the distillation, the pure product was transferred into a labelled tared container from where it was taken for infra-red spectroscopy.

At each stage, colour changes, gaseous evolution and smell of the solution and product were carefully noted.

RESULTS

Observations: During the experiment, the solution under reflux changed from colourless to pink colour and eventually turned into an orange colour.  Some of the anti-bumping granules remained undissolved in the heated solution.  The solution separated into two layers; an upper layer of orange solution and a lower layer of colourless solution after adding 20ml of diethyl ether.  When Na2CO3 solution was added, effervescence occurred where CO2 was released.  Pressure was created inside the separating funnel as the stopper was placed on the funnel and had it inverted, however, the pressure got reduced as the separating funnel was continually inverted.  Two distinct layers were also formed as before.  The MgSO4 clustered together after sometime as it absorbed water.   A clear orange solution was observed when the MgSO4 was filtered off.  The colour of the product was orange and had a sweet fruit flavouring smell, which showed that an ester was synthesised.

 

DISCUSSIONS

The fingerprint regions of the two esters are almost the same.  From the product’s spectrum, the circle marked 1 is steeper as does the I.R spectrum of the expected spectrum with a wave numbers of 600cm-1.  So does the circle marked 2 and 4 with the same wave numbers and shapes.  There is a slight difference in the shape of the rectangles marked 3.  The spectrum of the ester synthesised has many waves than the expected spectrum which has a broad edge.  The part labelled 5 in the spectrum of the synthesised ester is slightly broader compared to the expected spectrum.  Although, there are slight irregularities in the fingerprint regions, the spectrum confirms that the product synthesised was an octyl ethanoate.

Some errors that may have also occurred during the experiment could have been the presence of some minute volume of water in the ester.  This will affect the infra-red spectrum of the ester synthesised.  Therefore, the experiment could be improved by extracting as much water molecules as possible from the ester during the distillation process.

During the experiment, sulphuric acid was added to serve as a catalyst to speed up the rate of reaction by lowering the activation energy and therefore, less time for the reaction to occur.  Heat was applied so as to increase the temperature of the system, and therefore, increase rate of reaction as organic reactions are always slow.  The warmed solution was placed in a crushed ice to speed up the cooling process.  Again, anti-bumping granules were added to avoid production of large gas bubbles which cause liquid to splash over into the condenser, thereby, producing an impure product; therefore, it absorbed more water (Beavon, 2001).  Excess of ethanoic acid was added so as to drive the equilibrium to the right and to synthesise a pure ester (Winova State University, n.d).  Sodium carbonate was added to remove any excess acid present.  The two layers were formed since water and diethyl ether are immiscible.  The upper layer made of the ether contained the ester while the lower aqueous layer contained water.  Magnesium sulphate was also added so as absorb any excess water molecules present since MgSO4 is hygroscopic.  

CONCLUSION

The spectrum proves that an ester, octyl ethanoate was synthesised.  The finger print region of the synthesised ester is characteristic of an ester’s finger print region.  The wave numbers and percentage transmittance are specific to each bond cleavage of an ester’s spectrum, thereby confirming that octyl acetate was synthesised.  Again, the orange colour and sweet orange smell of the product confirmed that octyl acetate has been synthesised.  

LIST OF REFERENCES

Aim

The aim was to determine the concentration of Sodium Hydroxide.

Safety

In order to prevent any accidence during the titration process, some safety precautions were observed.  Goggle was used throughout the experiment to prevent the corrosive action of Sodium Hydroxide solution from reaching the eyes.  Gloves were tightly worn on the two hands to avoid the corrosive action of the base.  The conical flask containing the KHP solution was hold firmly to the table surface to avoid it from falling off the table in the process of sucking the base.  The table surface was clean of all the spills to avoid skin contact.  Again, all chemical used were disposed of properly after the titration.

Equipment

  • 50cm3 burette,
  • 25cm3 pipette,
  • 250cm3 beaker,
  • Ring stand with clamp,
  • Funnel,
  • 250ml Erlenmeyer (conical) flask,
  • White tile,
  • Sodium Hydroxide solution,
  • Potassium Hydrogen Phthalate and

Methods

The burette was first rinse with the solution of NaOH (aq) and then fill with same solution measuring up to the zero mark.  The initial burette reading was read and record made in the trial column.  Again, the pipette was rinse with KHP, filled up to the 25 cm3 using the pipette filler, and then carefully transferred to the 250cm3 conical flask.  Added to the KHP solution was the phenolphthalein solution and then was mix together.  Here, there was no colour change.

The white tile was place on the ring stand.  Then the beaker containing the NaOH solution was place on the tile for optimum visibility.  The tap was open to run the NaOH solution into the flask.  The flask was kept swirling as the NaOH solution drops into the beaker directly above it until the solution turns pink.  The final burette reading was then determined and record in the trial column of the result table.

The burette was again top with NaOH solution and the initial reading recorded to the nearest 0.05cm3.  Then 25cm3 of KHP solution was suck using the pipette filler and gently poured into the conical flask from where phenolphthalein indicator was add and then mix together.

The NaOH solution was titrated against the 25cm3 of KHP solution in the flask placed on the white tile, swirling in the process.  After sometimes, the tap of the burette was control to release the base drop by drop to determine a sharp change in colour from colourless to pink.  At this point, the tap was close and record made of the final burette reading in the result table.

The titration process was repeated thrice and the values of the initial and final burette readings were written down in each of the titration.

Finally, the burette was empty and washed after the titration.  The end point was calculated and recorded in the column provided in the result table. The indicator used was record as phenolphthalein solution.  The concentration in mol/dm3 of the KHP solution was also record as well as the volume of the KHP solution used.

Results

Indicator used: phenolphthalein solution

Pipette solution: Potassium Hydrogen Phthalate. Concentration used (mol/dm3).............................................................................. 0.1M Volume used (dm3).................................................................................................0.025dm3

Discussion

If the burette were not rinse with the NaOH solution before the titration begins, the concentration of the solution would had been affected.  This is because during the cleaning of the burette with water, some bubbles of water may have been left inside, which if not removed will decrease the concentration of NaOH solution.  It is also necessary to rinse the pipette with the KHP solution, which would have if not removed, affected the reading of the titration by reducing the concentration of the KHP solution and the end point.  In addition, if the tip of the burette were not fill before the titration begins the volume of the NaOH solution would differ from the supposed volume.  This is because, it would appear more volume of the NaOH has been use than has been dispensed and so increase the concentration.  Addition of KHP solution to a beaker containing some water molecules will have no effect on the concentration of NaOH solution.  This is because the KHP solution already has a fixed number of moles.

The base is titrated against the acid using phenolphthalein solution as the indicator to detect easily the colour change from colourless to pink. It is advisable to remove the sodium hydroxide from the burette as soon as possible after the titration to prevent the tap, tip and inside of the burette to be attack by the NaOH solution. This is because; the NaOH would react with the glass and block the tip of the burette.

The concentration of the NaOH solution from the result is 0.118M.  This shows a slight deviation from the supposed concentration of 0.12 by 0.002M. This is by far insignificant.  This error may have occurred during the titration process.  Excessive running of the NaOH solution from the burette may have caused the change, even after the colour has changed to pink.  In addition, it has been cause by the change in the concentration of the NaOH solution due to its hygroscopic nature and ready absorption of CO2 on exposure.  Finally, the change in the titre value may have also resulted from the above factors.  The titre value changes from the supposed 20.8cm3 to 21.1cm3 showing a difference of 0.30cm3.  To improve on the result, PH indicator should be used to detect easily the end point.

Potassium hydrogen phthalate is a primary standard with a high purity and large molecular mass.  However, a weak acid, it reacts with NaOH solution.  It has a known concentration and so the concentration of NaOH could be calculated as shown on the result page.

According to Jenkin (2003), a primary standard can be easily weighed out and prepared as a solution of known concentration, which will be useful for calculating the concentration of another solution.  Therefore, KHP contains no water of crystallization; is not affected by exposure to air- CO2, water vapour or O2.  These properties serve as potential reasons why KHP solution can accurately determine the concentration of an unknown solution in a titration reaction.

Conclusion

A known solution of chemical substance can be used to determine the unknown solution of another substance in a titration reaction.  

References

 
Crude oil fractions are in high demands in industries such as petrochemical industries, plastic industries, and transportation industries, for home use and others.  For example, statistics released in February 2010 by the Organisation Of Petroleum Exporting Countries (OPEC) shows that oil production rose to 29.31 million barrels per day (bpd), an increase of 60,000 bpd, a platts survey has revealed (Ward, 2011).    This shows the significance of crude oil around the globe as an energy source.  Therefore, the necessity for crude oil to be separated into its different constituent fractions to meet its daily demands in various applications.  The separation of crude oil into its component fractions is feasible as it contains hydrocarbons - an organic compound made up of carbon and hydrogen atoms only (Franklin, n.d).  These fractions have different boiling points due to the chain length of the hydrocarbons.  This enables them to condense below their boiling points in the fractionating column.  The method of separating crude oil into its different fractions using their boiling points is called fractional distillation.  Therefore, fractional distillation of crude oil is the mechanical separation of various fractions of petroleum using external heat in a fractionating column called tower (ExxonMobil, n.d).  This occurs due to differences in boiling points of the hydrocarbon contained in the crude oil.  This essay will feature some of the stages involved in distillation process, such as removal of water, inorganic impurities before the fractional distillation.  It will also emphasize on some other refining process that take place in the refinery industries.

Firstly, water and demulsifiers such as the mixture of chemical called polyoxylalkylated alkyl phenol formaldehyde poly condensates with disocyanated compound (Keefer, 2000) is reacted with the crude oil and then heated.  After sometimes, salts, water and traces of metals separate out in a tank.  These impurities settle down and are then filtered off (Cleveland, 2007).

Secondly, the impurity-free petroleum is heated to a very high temperature of about 400-4300C in an iron retort where it gets vaporised.  The vapour is then directed into a fractionating column, made of cylindrical steel about 31 meters high and 3 meters in diameter (senapati, 2006).    At this phase, additional heat is subjected to the flash-tower vapour making it more energetic to move up the fractionating column.  Here, residue pitch or petroleum coke with large carbon atoms of 30 and above condenses, due to their high boiling points, into a horizontal plate called tray placed in each column.  As the vapour moves up the fractionating column, fractions whose boiling points are below the temperature of each column condense and are being received by the collecting tray.  Heavy oils such as lubricating oils, petroleum jelly, grease, paraffin wax with 17-30 carbon atoms condense below their boiling points.  As the vapour move up the fractionating column, the temperature of the system drops off.  The next fraction that condenses is diesel oil with 10-18 carbon atoms at a temperature of about 250-3200C followed by kerosene with 10-16 carbon atoms at a temperature of about 180-2500C.  As the vapour continuously rise up the fractionating column, Naphtha, petrol, petroleum ether each with 9-10, 5-10, 5-7 carbon atoms condense at a temperature of about 120-1800C, 40-1200C and 30-700C respectively (senapati, 2006).  Finally, molecules such as methane, propane are collected as gases at the end of the column at a temperature of about 300C as they do not condense.  These gases are called refinery gases.

Conversion follows immediately after separation where some less demanding fractions of petroleum are converted into useful products of higher demands in industries.  This process of conversion involves any one of cracking, isomerisation or reforming requiring high temperature, pressure and catalyst. (ExxonMobil, n.d).

In conclusion, crude oil distillation is a very complex process, starting from the removal of impurities up to the separation of the different fractions, requiring a lot of resources in terms of human labour and money.  The removal of impurities makes the process more efficient as water and other impurities such as sulphur are removed.  The different fractions derived from crude oil depend on the number of carbon atoms they contain and the temperature at which each of the fractions boils and then condenses. In general, the higher the hydrocarbon, the higher the boiling points.  The conversion process is necessary as less demanded products of the fractions are converted to more useful products such as petrol and diesel.  Though a non-renewable source of energy, its fractions are found useful in most industries, homes and factories.  For example, the bitumen derived as a solid fraction of petroleum is used in road constructions as tar; in the manufacture of printing ink and rubber when added with oil.

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Summary Note

The journal emphasises on the opinions by a writer- Robert phillipson and facts as proven by Joseph Bisong, a Nigerian on the impacts of English language and foreign culture on some countries by some English-speaking countries.  Phillipson argues in his book, “linguistic imperialism” that there has been a language and cultural imposition on some regions of English- speaking countries. (Joseph, B., 1995).

Joseph, (1995) writes to counter the judgment by phillipson.  He argued that English has not succeeded in replacing the local language of countries colonised in the past like Nigeria, but has served as a means through which Nigerians are being united, since the country is multilingual and that Nigerian languages are still being spoken by its citizens irrespective of the use of English as the official language of the people. Joseph also added that by speaking English, a child becomes bilingual which gives the child an added advantage in communication skills.  Secondly, Joseph also disagreed with Phillipson’s view that the dominance of English has made the culture of countries like Nigeria inferior and marginalised.  He stated that English has not on the whole change the psychological structure of Nigerians (pg. 127), where he cited politics as an exemplary case study in Nigeria.

Finally, Joseph advocated that it will sound ridiculous that Nigerian creative writers are affected by centre linguistic and cultural imposition, rather these creative writers decided to write in English based on their psyche at the moment since writing in English was a medium of mutual communication based on the historical background of Nigeria (pg. 130).  Therefore, writing in one’s native language is feasible, but will not properly disseminate one’s ideas to the general public. (Joseph, B., 1995).

Reference

  • Joseph, B. (1995) Language choice and culture imperialism Oxford University Press.
 
Students tend to cross international borders in pursuit of a quality and sound education not provided by their home countries, especially in their choice of courses.  Statistics released by the Higher Education Statistics Agency shows that a total figure of 368,970 non-UK students for 2008/09 against the 325,985 in 2007/08 which indicates an 8% increase.(UKCISA, n.d)

Although, students migrate to study abroad, they face some unusual problems generally referred to as “culture shock”.  Paul (1995) sees culture shock as an internationalised perspective developed in international students in response to an unfamiliar situation.  Students at first in a foreign country feel excited and comforted due to things they see that impress them, but with time, they look sad, frustrated and homesick.  This literary piece will feature some of these difficulties and solutions that can be proffered to them.

Research indicates that mutual communication between home and international students is a problem.  According to UKCISA (2008), international students find it difficult to understand the accent of their new environment.  This affects students in class as they find it difficult to understand lecturers.  This problem is mostly seen within students from non-English speaking countries like Asia especially in speaking, listening, writing and pronunciation. (Soyoun Park, 2006).  In addition, they also face the problem of acclimatising to the climate of the place.  Personal experience shows that students from temperate regions find it difficult to quickly adapt to the cold weather in the UK.  This adverse weather prone students to health issues like cold, cough which affect students’ academic performance.

The fact that every problem has solutions means that there are optimistic solutions to the afore-mentioned problems of international students.  University of Leeds’ language centre (n.d) suggests that tutors should always try to pair students in classrooms, activities, sports, etc and also introduce new students to older students in their departments who are of the same country with the new students.  The language centre further stated that tutors should encourage new students’ participation in other social and academic programmes like clubs and society, seminars, students’ union, etc.  By forming new students into groups for class discussions, seminars and activities with home students, these new students find it easier to learn the accent of the people.  They also familiarise themselves with some peculiar phrases, slangs, abbreviations and phonetics as used by their co-home students.

According to University of Bristol (2010), students can overcome the communication problems by watching TVs, films, listening to radio broadcast, and making new friends with the home students.  It also suggested that new students should read books, newspapers, novels and also introduce themselves to neighbours and attend any British family invitation for international students.  In addition, new students should also contact the language centre of their University and listen to discussions, tapes and videos.  This helps them to develop their language and communication skills.

Again, students can reduce the effect of the adverse cold weather of their new environment by layering their clothes-like wearing shirts under woollen pullover and jackets that can prevent cold from penetrating their skin.  They also need thermal under wears to keep them warm and shoes like rain boats. (UKCISA, 2010).  In addition, before students’ departure from their home countries, they should be oriented by their travelling agencies on the weather condition of their destinations to be in order to reduce the traumatic effects of culture shock on them.  Students should also, on arrival get registered with a General Practioner (GP) as recommended by the school for any emergency that may occur as a result of the weather. (UKCISA, 2010).

Conclusively, although all the solutions mentioned above are necessary to alleviate the difficulties faced by international students, there are some that require urgent implementation in order for international students to achieve their goals and aspirations and for safety and continuity of life.  Amongst these are pairing international students with home students in class discussions, seminars, and group work, which is more likely to help international students combat the problem of communication in English language as compared to introducing new students to old students as suggested by the Language Centre-University of Leeds.  This is because pairing or grouping students by mixture of home, old and new students enables the new students to learn the speaking and listening skills of home and old students.  This makes them feel at home and exposes them to making new friends thereby relieving them of loneliness.  Moreover, regular listening to conversations, news, shows, etc on radios, TVs and the materials in the Language Centre assist new students’ performance in English especially Asians. On the contrary, watching TVs, films, etc may consume students’ time that should have been used for reading, studying, and so it is not a reliable factor to the solution of the problems of foreign students as they even spend more on TV licence and cinemas. Though students are oriented before arrival, it is also not a reliable solution to the problems because culture shock is natural. Finally, Wearing winter clothes and thermals will help prevent students from the effects of cold like in the winter.

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