Question

Give one example of a chemical reaction characterised by a change in state.

Answer 1

The combustion reaction of candle wax is characterised by a change in state from solid to liquid and gas.

When a wax candle burns, the solid wax reacts with oxygen to form carbon dioxide gas and water. At room temperature, candle wax is a solid, the carbon dioxide formed is a gas, and the water formed by the combustion is a liquid. Therefore, the physical state changes from solid to liquid and gas.

\[\ce{Wax_{(solid)} + O2_{(g)} -> CO2_{(g)} + H2O_{(l)} + Heat + Light}\]