Lab - Ascorbic Acid Analysis

Question 1

T or F

Ascorbic acid is extremely labile on exposure to heat and air, except in alkaline media.

Answer 1

F

acid dapat

Question 2

Chemical methods for the determination of Vitamin C are based on \_\_\_ of the vitamin
A. reducing properties
B. polarity
C. both A and B
D. neither A nor B

Answer 2

A

Question 3

titration method of determination: iodine + acid extract, with \_\_\_(indicator) in the presence of light/an oxidizing agent
A. phenolphthalein
B. bromcresol green
C. methylene blue
D. all of the above

Answer 3

C

Question 4

Which is not part of the fluorometric method of determining VitC?
A. reduction to dehydroascrobic acid
B. reaction to 0-phenylendamine
C. both are part
D. both are not part

Answer 4

A

oxidation dapat

Question 5

What method + specific modification of it does the FNRI employ for Ascorbic Acid determination?

Answer 5

Bolin and Book modification of Roe and Oesterling colorimetric method

Question 6

What method was used for the experiment?

Answer 6

Roe and Kuether method

Question 7

Which acids function to reduce the pH of the extracting medium?
A. Acetic and trichloroacetic
B. Trichloroacetic and oxalic
C. Acetic and oxalic
D. Oxalic and metaphosphoric

Answer 7

D

Question 8

By shaking with __, the ascorbic acid is oxidized to dehydroascorbic acid

Answer 8

“Norite”

Question 9

Function of thiourea

Answer 9

Stabilize Vitamin C

Question 10

After coupling with ___, the solution is treated with H2SO4 to produce a red color, to be measured photometrically

Answer 10

2,4 dinitrophenylhydrazine

Question 11

In the standard curve, identify the ordinate

Answer 11

Optical density values

Question 12

In the standard curve, identify the abscissa

Answer 12

Concentration of ascorbic acid