internal assessment vitaminC

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Zubair Abdur Rahim bin Ahmad

M08L

Measuring the concentration of vitamin C

Introduction 

 Refer to Biology Handbook page 159

Aim

To uncover the effects of heat on the amount of vitamin C in foods

Research question

What are the relationship between the length of time lime juice is boiled and the concentration of vitamin C in the lime juice sample?  

Hypothesis

The longer the lime juice is boiled, the lower the concentration of vitamin C in the lime juice sample will be.

Variables

Independent variable: duration of boiling: - 0 min (fresh lime juice ), 10 min, and 1 hour

Dependent variables:  Concentration of vitamin C in lime juice sample                          

Fixed variables:

 1. Type of juice - Lime juice will be used throughout the experiment

 2. Volume of DCPIP used in each titration - only 1 cm3 of DCPIP will be used in each titration

 3. The person who decide whether the colour change of DCPIP - The same person will decide     whether the DCPIP had reduced to colourless solution or not.

4. Environment - the experiments will be conducted at the same place so that the temperature and pressure of surrounding will be constant.

Apparatus and Materials

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Method

  1. Measure 10cm ³ of glacial acetic acid, 4cm³ of appropriate juice and mix it together with distilled water until it make up of 100cm³.
  2. Fill a burette with this solution and note the burette reading.
  3. Use a syringe to transfer 1 cm³ of D.C.P.I.P into a conical flask and titrate.
  4. Add the juice, one drop at a time until the blue D.C.P.I.P is reduced to a colourless solution.
  5. Repeat for the other juice samples, then repeat the whole procedure.
  6. Calculate using the results obtain the concentration of ascorbic acid in each of the juice ...

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