Question

Hydrocarbons on burning in the air give carbon dioxide:

• A. water and heat
• B. carbon monoxide and heat
• C. water and carbon monoxide
• D. water and sulphur dioxide

Answer 1

The correct option is A water and heat

Hydrocarbons burning in air will give off carbon dioxide, $C{O}_2$, carbon monoxide, $CO$, water, $H_{2}O$ and, if there is not enough air, some carbon in the form of soot. These reactions will be accompanied by the release of heat and light.

The energy required to break the bonds in the hydrocarbon molecules is substantially less than the energy released in the formation of the bonds in the $C{O}_2$ and $H_{2}O$ molecules. For this reason, the process releases significant amounts of thermal energy.