Signs of a chemical reaction that are observed when burning a candle.

When a candle burns, both physical and chemical changes take place.

Chemical changes. When you light the candle, the wax next to the wick will melt. The wick absorbs liquid wax. Liquid wax is vaporized by the heat generated by the flame. This vapor of wax burns near the flame and produces new substances such as carbon dioxide, carbon black, water vapor, heat and light. This is an irreversible change.

Physical changes. When heated, candle wax melts and forms a liquid wax. This is a physical change. As it turns back into hard wax when cooled. This is a reversible change.