Chemical tests

Question 1

What does Benedict’s Test test for?

Answer 1

Reducing and non-reducing sugars

Question 2

What does the emulsion test test for?

Answer 2

Lipids

Question 3

What does the Biuret Test test for?

Answer 3

Peptide bonds (proteins)

Question 4

How do you test for starch?

Answer 4

Add iodine solution. If starch is present, the solution will turn from orange red to blue black

Question 5

Which test would you carry out to test for proteins?

Answer 5

The Biuret test.

Question 6

How would you carry out a test to show the presence of proteins?

Answer 6

Crush/liquify the what you’re testing. Add an equal amount of biuret reagent. If proteins are present, it will turn from blue to lilac/purple

Question 7

How would you carry out a test to show the presence of reducing sugars?

Answer 7

Add copper sulfate (CuSO4) and heat in a water bath for 5 mins. If reducing sugars are present, a brick red precipitate will form. (Green–>violet–>orange–>red)

Question 8

How would you carry out a test to show the presence of non reducing sugars?

Answer 8

Carry out a Bendict’s test. If there is no colour change, take a new sample and add HCl to it. Heat it in a water bath for 5 mins, then add NaHCO3. Then redo Benedict’s test.

Question 9

How would you carry out a test to show the presence of lipids?

Answer 9

Add ethanol, shake, then add water gently on the side. If lipids are present,a cloudy layer will form on the top