Chemistry - Biomolecules Question with Solution | TestHub

The hydrolysis of sucrose by boiling with a mineral acid $(\mathrm{HCl})$, produces a mixture of equal molecules of $D$-glucose and $D$-fructose. Sucrose solution is dextrorotatory, specific rotation $=+66.5^{\circ }$. But on hydrolysis, it becomes laevorotatory. The specific rotation of $D$-glucose is $+52^{\circ }$ and of $D$-fructose is $-92^{\circ }$. Therefore, the net specific rotation of an equimolar mixture of both is : $\frac{+52^{\circ }-92^{\circ }}{2}=-20^{\circ }$ $\therefore$ laevorotatory.