(N/A) Complete combustion of alkane: Alkanes on heating in the presence of air or dioxygen are completely oxidized to carbon dioxide and water with the evolution of a large amount of heat.
The general reaction for the combustion of an alkane is:
$C_{n}H_{2n+2} + (\frac{3n+1}{2}) O_{2} \rightarrow n CO_{2} + (n+1) H_{2}O + \text{Heat}$
Examples:
$(i)$ Methane: $CH_{4(g)} + 2 O_{2(g)} \rightarrow CO_{2(g)} + 2 H_{2}O_{(l)}$ ; $\Delta_{c} H^{\ominus} = -890 \ kJ \ mol^{-1}$
$(ii)$ Butane: $C_{4}H_{10(g)} + \frac{13}{2} O_{2(g)} \rightarrow 4 CO_{2(g)} + 5 H_{2}O_{(l)}$ ; $\Delta_{c} H^{\ominus} = -2875.84 \ kJ \ mol^{-1}$
Due to the evolution of a large amount of heat,alkanes are used as fuels in homes,vehicles,and industries.
$(b)$ Incomplete combustion of alkane: During incomplete combustion of alkanes with an insufficient amount of air or dioxygen,'carbon black' is formed.