Natural gas is primarily composed of methane, but it also contains small amounts of propane,

ethane, butane, etc. Let$$s assume that natural gas can be modelled by a mixture of methane

and propane. If the volume fraction of propane is $\backslash$alpha $,$ that is $\backslash$alpha $=$ nC$3$H$8/($nCH$4+$ nC$3$H$8),$ estimate

the natural gas heat of combustion $($HOC$)$ as a function of $\backslash$alpha $.$ Plot HOC for $\backslash$alpha ranging between

$0\mathrm{.}5$ and $1.$ Assume the fuel$/$air equivalence ratio is unity.