Question

The burning of a candle is a chemical change whereas the melting of a candle is a physical change. Why?

Answer 1

Physical change

• The changes which can be observed and specified like changes in hardness, rigidity, fluidity, color, density, boiling point, melting point, etc. are the physical changes.

Chemical change

• A chemical change is a change that results in the formation of new chemical substances.
• It involves the making or breaking of bonds between atoms.

Burning of candle

• When a candle burns, the oxygen in the air reacts, formation of carbon dioxide takes place.
• Hence burning of candles is a chemical change.

Melting of a candle

• Candle wax melts when it is heated. When it cools, it transforms back into solid wax.
• The melting of a candle is physical change as no new product is formed.