(Practical) Vitamin C

Question 1

What is the independent variable?

Answer 1

Fruit juice

Question 2

What is the dependent variable?

Answer 2

Volume of juice required to decolourise 1cm3 of DCPIP from blue to colourless

Question 3

What is a control measure?

Answer 3

A known vitamin C solution

Question 4

What are some control variable?

Answer 4

Concentration of DCPIP (1%), volume of DCPIP, same end point colour

Question 5

What is the method for this experiment?

Answer 5

1. Pipette 1cm3 of DCPIP into a beaker/test tube
2. Using a burette add the vit. c solution drop by drop
3. Swirl the beaker gently , and continue until the DCPIP has decolourised
4. Record the volume of solution that has been used
5. Repeat a further 2 times
6. Repeat the method for different fruit juices

Question 6

What are some possible evaluation issues?

Answer 6

Difficulty controlling temperature
End point can be subjective
Loss of solution when transferring from one beaker to another
Accuracy of measuring equipment and manufacturing errors