To test for non-reducing sugars:

Question 1

1. Add ……………. to the sample and heat in a …………. that has been brought to the boil

Answer 1

dilute hydrochloric acid

water bath

Question 2

2. Neutralise the solution with ………………..

Answer 2

sodium hydrogen carbonate

Question 3

Use a suitable indicator (such as red litmus paper) to identify when the solution has been neutralised, and then add a little more ……………. as the conditions need to be slightly ………..for the Benedict’s test to work

Answer 3

sodium hydrogencarbonate

alkaline

Question 4

Then carry out the ……… test as normal; add ………. reagent to the sample and heat in a water bath that has been boiled – if a colour change occurs, a reducing sugar is present

Answer 4

Benedict’s

Question 5

Why do you have to do the steps before doing normal benedict’s test

Answer 5

The addition of acid will hydrolyse any glycosidic bonds present in any carbohydrate molecules

The resulting monosaccharides left will have an aldehyde or ketone functional group that can donate electrons to copper (II) sulfate (reducing the copper), allowing a precipitate to form