Practical investigations
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I am doing an investigation into the effects of cooking on fruit and vegetables. I can make the solution up from the fruit by adding 100 cm3 of distilled water to 100 g of fruit but how will I be able to find the concentration of vitamin C if I have diluted it in the first place?
Is there any other method I could make up the solution?
Igloo says ...
After you have added the 100 cm3 of water to the fruit, you will need to use a method to extract the vitamin C into this water. This may involve the use of a liquidiser. Next you will need to separate the liquid from the fruit pulp, perhaps by filtration through muslin. Then you must make this solution up into a known volume of solution in a volumetric flask – perhaps 250 cm3 – and titrate portions of known volume (say 25 cm3) with a suitable reagent - perhaps DCPIP.
Assuming that all the vitamin C has been extracted from the fruit into the solution, and using the example above, all you need to do is to calculate the mass of vitamin C in the 25 cm3 portion, and then multiply by 10 to determine the mass of vitamin C in the original 100 g of fruit.
Always carry out a risk assessment and check with your teacher before starting any practical work.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 14 December 2006
