Benedicts reagent

-Add Benedict’s reagent (which is blue as it contains copper (II) sulphate ions) to a sample solution in a test tube.

-Heat tube in water bath or water which has been boiled for a few minutes

-If reducing sugar is present, coloured precipitate will form as copper (II) sulphate is reduced to copper (II) oxide, which is insoluble in water.

-It is important that an excess of Benedict’s solution is used so that there is enough copper (II) sulphate present to react with any sugar present.

-Positive test result = Colour change, colour scale from blue (no reducing sugar), through green, yellow and orange (low to medium concentration of reducing sugars) to between brown/ brick red (high concentration of reducing sugar).

Test is semi quantitative as degree of colour change can indicate how much (the concentration of) reducing sugar is present.