Investigate the lowest concentration of copper (II) sulphate that will bring about the full denaturation of egg albumen.

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Investigation into the effect of concentration of copper (II) sulphate on the denaturation of egg albumen

The aim of this experiment is to investigate the lowest concentration of copper (II) sulphate that will bring about the full denaturation of egg albumen.  I will achieve this by diluting 0.1 mol dm3 copper (II) sulphate ten times to acquire 10 consecutively more dilute solutions.  These will then be added to the same volume of egg albumen.  The experiments will be performed at room temperature and the extent of denaturation will be decided on the ‘opaqueness’ of the albumen.

Prediction

I predict that the lowest concentration of copper (II) sulphate will be around 0.01 – 0.02M.  This is because of the following reason.  Copper ions in copper (II) sulphate are highly electropositive.  Within proteins exist ionic bonds, which form between amine and carboxylic terminals resulting in polarised R groups.  Due to the high positive charge of the Cu2+ ions, when copper ions are in the presence of the R groups, they are pulled toward the negatively charged R groups.  The copper ion then forms an ionic bond with the polarised R group, which is stronger than the already existing bond.  As a result, the existing bonds are broken and the protein changes shape.  This change in shape is responsible for the denaturation.  At a lower concentration of copper (II) ions (smaller overall concentration), there will be less R groups disrupted as all the copper ions would have bonded with R groups.  These would leave other proteins unaffected, which would result in only partial denaturation.  This hypothesis is the reason for my prediction.

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Preliminary Tests

Preliminary tests showed that five minutes was enough to allow time for denaturation to occur in the stronger solutions.  The opaqueness of all the variables that had fully denatured were almost identical providing an easy comparison with the solutions that did not denature.  The variables used in this plan also provide a sufficient range.

Equipment

Black card, 3cm3 syringe, graduated pipette, ten test tubes, test tube rack, beaker, stopwatch and goggles

Method

  1. Measure out 2ml of egg albumen into a test tube using a syringe
  2. Add 10ml of 0.1mol dm3 copper ...

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