Courseworks

An experiment to show the lowest concentration of copper (II) sulphate solution needed to bring about full denaturation of egg albumen

Egg albumen is a complicated protein that is more commonly know as egg white. This protein becomes denatured when copper (II) sulphate is added at a certain concentration. This is because the cations from the copper ions react with the amino acids carboxylate anions which form peptide bonds. This in turn affects the secondary structure of the egg albumen since there is a disruption in the peptide bonds and the protein reforms as a fibrous protein precipitating out of the solution and becoming opaque, the copper ions also react with the hydrogen in the amine group causing the primary structure to fail also. Another reason for the opaqueness is that the positive copper ions change the polarity of the albumen; this increases its insolubility and causes it to precipitate out of the solution.List of apparatusColorimeter I have chosen this method of measuring the opaqueness of the egg albumen because it is a lot more accurate than eye and will give me figures that I can use in graphs, tables or charts.Distilled water this is use rather than tap water because it contains less impurities that could affect the experiment (e.g. copper ions from copper pipes.) results. It can also be used to clean other apparatus.Egg albumen this is needed to perform the experiment0.1 mol dm-3 copper(II) Sulphate solution I will use this to make all my concentrations, e.g. 0.05, 0.025 etcTest tubesTest tube rackPipettes and syringes these will be used to measure certain amounts accuratelyPreliminary workFrom looking at the results I have gathered. It showed me the importance of the range of concentrations used. My results were reasonable I know this because they were similar 2 most of my class matesThis also helped me narrow down the range of result I would take I decided that I would only take between0.005 and 0.00625PredictionI predict that it will totally denature between 0.0125 mol dm-3 0.025 mol dm-3 because this is the range that not only my preliminary results support but also that which makes sense.Method1) Take 12 test tubes and make up solutions of 3 solutions of each of the following concentrations 0.05, 0.025, 0.0125, 0.00625.To make a solution of 0.05 mol dm-3 take 25cm3 of 0.1 solution and add 25 cm3 of distilled water. Then take 15cm3 of this solution out it to one side.To make 0.025 solution take the 35cm3 and add a further 35 cm3 and take 15 of this and so on.2) Transfer 5 cm3 of each of the solutions into a test tube label the test tube according to its concentration.3) Now add 5 cm3 of egg albumen to each test tube shake to mix and then wait for 5 minutes4) Shake the test tube again and wait for a further 5 minute to make sure all possible denaturation has taken place5) Make sure the colorimeter has the right filter in and is set to zero6) Take each test tube and put a sample of each into a curvet (making sure the clear ends are not dirtied) place the curvet in to the colorimeter and take a reading7) Record a reading for each sample and put into a graph and table discarding any anomalous results.SafetyEnsure that great care is taken when handling copper sulphate. Ensure safety glasses are worn at all times and a lab coat to protect clothing.

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