Vitamin C content (2)

Question 1

Devise an investigation to measure vitamin C content in samples of broccoli:

Answer 1

1)Extracting juice
2)Titration, adding drops of this juice to controlled volume of DCPIP, count number of drops required to turn it from blue color to colorless
3)Compare results to calibration graph to find vitamin c concentration in the juice

Question 2

How does DCPIP change color in presence of vitamin C?

Answer 2

Vitamin C is a reducing agent, adds an electron to the DCPIP

Question 3

Control variables:

Answer 3

Temperature
Concentration of DCPIP (1%) and volume (1cm3)
Shake each tube same number of times (e.g. 3 times)
Same end point colour, when blue colour just about disappears