Experiment No. 11

Question 1

Result of fructose in Benedict’s test.

Answer 1

dark orange

Question 2

Result of sucrose in Benedict’s test.

Answer 2

olive green

Question 3

Result of starch in Benedict’s test.

Answer 3

no changes of color

Question 4

Result of xylose in Benedict’s test.

Answer 4

red solution was observed after heating

Question 5

Result of fructose in Molisch test.

Answer 5

purple ring

Question 6

Result of sucrose in Molisch test.

Answer 6

purple ring

Question 7

Result of starch in Molisch test.

Answer 7

brown ring

Question 8

Result of xylose in Molisch test.

Answer 8

purple ring

Question 9

Result of fructose in Barfoed’s test.

Answer 9

brick-red precipitate (2 minutes)

Question 10

Result of sucrose in Barfoed’s test.

Answer 10

brick-red precipitate (2 minutes)

Question 11

Result of starch in Barfoed’s test.

Answer 11

green (2 minutes)

Question 12

Result of xylose in Barfoed’s test.

Answer 12

red precipitate (1 minute & 45 seconds)

Question 13

Result of fructose in Seliwanoff’s test.

Answer 13

yellow to red

Question 14

Result of sucrose in Seliwanoff’s test.

Answer 14

yellow to red

Question 15

Result of starch in Seliwanoff’s test.

Answer 15

no changes

Question 16

Result of xylose in Seliwanoff’s test.

Answer 16

no changes

Question 17

they are reducing agents (e.g. monosaccharides & dissacharides)

Answer 17

reducing sugar

Question 18

why sucrose is not a reducing sugar?

Answer 18

because the two monosaccharide units are held together by glycosidic linkage.

Question 19

how can Seliwanoff’s test be used to differentiate sucrose from fructose?

Answer 19

fructose turns red faster than sucrose.