PAG 9: Qualitative tests

Question 1

Biuret test tests for:

Answer 1

Proteins

Question 2

Iodine test tests for:

Answer 2

Starch

Question 3

Emulsion test tests for:

Answer 3

Lipids

Question 4

Benedicts Test tests for:

Answer 4

• Reducing Sugars
• Non-Reducing sugars

Question 5

Test strips test for:

Answer 5

Glucose

Question 6

Biuret test method:

Answer 6

1. Add sodium hydroxide solution.
2. Add copper (II) sulphate solution.

Question 7

Iodine test method:

Answer 7

1. Add iodine in potassium iodine solution.

Question 8

Emulsion test method:

Answer 8

1. Add ethanol.
2. Pour solution into water.

Question 9

Benedict’s test for Reducing sugars method:

Answer 9

1. Add benedict’s reagent to a sample and heat in a water bath to a boil.

Question 10

Benedict’s Test for Non-Reducing sugars method:

Answer 10

1. Add dilute HCl.
2. Put in a water bath brought to a boil.
3. Neutralise with sodium hydrogen carbonate.
4. Do Benedict’s test for reducing sugars.

Question 11

Test strips method:

Answer 11

Dip test strips in solution.

Question 12

Biuret test positive result

Answer 12

Blue –> purple

Question 13

Iodine test positive

Answer 13

Brown-orange –> blue-black

Question 14

Emulsion positive

Answer 14

Milky colour

Question 15

Benedict’s test positive

Answer 15

Sample goes from blue (to green to yellow to orange) to brick red precipitate, depending on the concentration.

Question 16

Test strips positive

Answer 16

Colour change will occur if glucose is present. Compare to chart of known colour changes to check for concentration.