determining the concentration of
vitamin C in fruit juice
PROCEDURE :
1. Fill 1ml of 1% DCPIP into three specimen tube with the label A, B and C.
2. Fill up syringe needle A with 5 ml of 0.1% ascorbic acid solution.
3. Place the tip of syringe needle A into specimen tube A and drip the ascorbic
acid solution into the 1% DCPIP solution while stirring slowly until the colour
of the DCPIP solution decolourise.
4. Record the volume of the ascorbic acid solution while decolourise the 1%
DCPIP solution in specimen tube A in Table 1.
5. Fill up syringe needle B with 5ml of fruit juice X and syringe needle C with 5ml
of fruit juice Y.
6. Place the tip of syringe needle B into specimen tube B and drip fruit juice X
into the 1% DCPIP solution and stir it slowly until the colour of the DCPIP
solution decolourise.
7. Record the volume of fruit juice X which decolourise the 1% DCPIP solution in
specimen tube B in Table 1.
8. Repeat step 6 by replacing syringe needle B with syringe needle C, specimen
tube B with specimen tube C and fruit juice X with fruit juice Y.
9. Record the volume of fruit juice Y which decolourise the 1% DCPIP solution in
specimen tube C in Table 1.
a) Complete the Table 1 below
b) State the variable in this experiment :
• The manipulated variable :
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• The responding variable :
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• The constant variable :
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c) Give one inference based on your observation in Table 1.
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d) Write the hypothesis for this experiment.
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e) On the graph paper provided, draw a bar chart to show the
concentration of vitamin C in every fruit juice.
f) Based on the bar chart you have drawn, state the relationship between
the type of fruit juice with the concentration of vitamin C
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g) If fruit juice X is kept at room temperature for a few hours, predict
the volume of fruit juice X to decolourise 1ml of 1% DCPIP solution.
Explain your prediction.
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