Chemistry Experiment 6

Question 1

Estimation of vit-C is done by which method ?

Answer 1

Iodometric Method

Question 2

Vitamin C also called as -

Answer 2

Ascorbic acid

Question 3

Vitamin C is oxidized to do what ?

Answer 3

To dehydroascorbic acid by iodine

Question 4

Aim of Estimation of Vit-C ?

Answer 4

To determine the amount of Vit-C sample volumetrically by Iodometric method.

Question 5

How is the concentration of Vit-C determined ?

Answer 5

The excess of iodine left behind is back titrated with standard sodium thiosulphate solution from the amount of iodine consumed, the concentration of Vit-C can be determined.

Question 6

What do Vit-C sample make in with which acid to prevent ?

Answer 6

Vit-C sample make in 4 % oxalic acid to prevent the reduction back to the ascorbic acid.

Question 7

_________+ I2 ——-> ___________

Answer 7

Ascorbic acid + I2 ——-> Dehydroascorbic acid

Question 8

Requirements of Estimation of Vit-C ?

Question 9

________+ I2 —(excess KI)—> ________+________

Answer 9

Na2S2O3 +I2 —(excess KI)–> Na2S2O3 + 2NaI

Question 10

Indicator of Estimation of Vit-C

Answer 10

Starch

Question 11

End point of Estimation of Vit-C

Answer 11

Blue to colorless

Question 12

Solution in burette

Answer 12

Na2S2O3

Question 13

Solution in flask

Answer 13

20 ml of 0.1 NI2

Question 14

Difference in standardization of I2 AND Estimation of Vit-C ?

Answer 14

Everything is same except that in estimation the prepared solution is kept in dark for 5 min and then starch is added & in standardization the starch is added early.