Carbohydrates: Monosaccharides

What is the general formula for monosaccharides?

(CH2O)n where n can be any number from 3 to 7

What is the meaning of a saccharide?

sugar

All monosaccharides are

reducing sugars

What is the test for reducing sugars?

Benedict's test

What is a reducing sugar?

Reduction is a chemical reaction involving the gain of electrons or hydrogen. Therefore, a reducing sugar can donate electrons to another chemical or the Benedict's reagent.

What is Benedict's reagent?

An alkaline solution of copper II sulfate.

What occurs when a reducing sugar is heated with Benedict's reagent?

It forms an insoluble red predicate of copper II sulfate.

What are the steps for the Benedict's test?

Add 2cm^3 of the food sample to the test tube.

If the sample is not in liquid form, grind it up in water.

Add an equal volume of Benedict's reagent.

Heat the mixture in a gently boiling water bath for 5 minutes.

What does each precipitate colour mean about the concentration of reducing sugars (all monosaccharides and some disaccharides)?

Blue -> None

Green -> Very Low

Yellow -> Low

Orange -> Medium

Red -> High