# Given DeltaH_"combustion"^@ for butane is -2657*kJ*mol^-1, what is "heat of combustion" for butane in J*g^-1?

Mar 22, 2017

$\text{Heat of combustion of butane}$ $\equiv$ $45.7 \times {10}^{3} \cdot J \cdot {g}^{-} 1$

#### Explanation:

We have data for the stoichiometric equation:

${C}_{4} {H}_{10} \left(g\right) + \frac{13}{2} {O}_{2} \left(g\right) \rightarrow 4 C {O}_{2} + 5 {H}_{2} O$ $\Delta {H}_{\text{rxn}} = - 2657 \cdot k J \cdot m o {l}^{-} 1$

Note that I halved the equation because it makes the arithmetic a little bit easier. I also had to halve the enthalpy change accordingly.

And thus $\text{Heat of combustion of butane}$ $\equiv$ $\frac{- 2657 \times {10}^{3} \cdot k J \cdot \cancel{m o {l}^{-} 1}}{58.12 \cdot g \cdot \cancel{m o {l}^{-} 1}} = 45.7 \cdot k J \cdot {g}^{-} 1$.