Core Practical 2

Question 1

What is the method of investigating vitamin C

Answer 1

• make different concentrations of vitamin C by serial dilution
• use a measuring cylinder to measure 1cm^3 of DCPIP solution into a test tube
• keep adding drops of each different concentrations of vitamin C to DCPIP solution then shake the test tube for a fixed set of time ( control variable) until it turns colourless
• count the number of drops then multiply by the volume on the graduated pipette
• repeat the experiment for the same concentration and calculate the average
• plot a graph of best fit which would get a calibration curve.

Question 2

What are the risks of this experiment and how to avoid them

Answer 2

DCPIP is irritant
- avoid contact with skin
- wear safety goggles

Question 3

What are the results

Answer 3

• as the concentration of vitamin C increases the volume required to decolories DCPIP will decrease
• the results should be plotted as the concentration of vitamin C against the volume required to decolories DCPIP
• the calibration curve can be used to estimate the concentration of vitamin C in a juice