Classification of Carbohydrate

1. Simple sugars

They are crystalline, soluble in water and sweet substances. They are grouped into monosaccharides like glucose, fructose and disaccharides like maltose, sucrose etc.

Monosaccharides have six carbon atoms per molecule.

E.g. C₆H₁₂O₆ (glucose). It turns brick red with Fehling’s solution. Monosaccharides are formed by hydrolysis of starch with dilute acid.

(C₆H₁₀H₅)_n  →  nC₆H₁₂O₆

Disaccharides – They contain twelve carbon atoms per molecule. It is formed by the condensation of two molecules of monosaccharides by the elimination of one molecule of water.

C₆H₁₂O₆ + C₆H₁₂O₆  →  C₁₂H₂₂O₁₁ + H2O_(L)

(2) Complex Sugars

These are the polysaccharides of long chains of monosaccharides linked together by condensation. Examples are starch and cellulose.