Question

Eating a chocolate and its digestion involve a physical change and a chemical change. Identify the changes, giving reasons.

Answer 1

Eating a chocolate and its digestion involve a physical change and a chemical change which are as follows:

• Melting of chocolate: While eating chocolate, the chocolate melts in the mouth. The reason for this is that the chocolate melts from a solid to a liquid state without undergoing any change in its chemical composition. There is no formation of a new chemical substance which makes it a physical change.
• Digestion of chocolate: Once ingested, the chocolate is digested in the abdomen with the help of gastric juices and enzymes to produce energy and ultimately Carbon dioxide $\left({\mathrm{CO}}_2\right)$ and Water $\left({\mathrm{H}}_2\mathrm{O}\right)$. As there is the formation of new chemical substances with different chemical properties than the starting material i.e., chocolate, it is a chemical change.

Physical change: A physical change involves the formation of no new substance and there is no change in the chemical composition of the substance undergoing the change.

Chemical change: A chemical change involves the formation of one or more new substances and there is a change in the chemical composition of the substance undergoing the change.