The enthalpy of combustion gives the heat released during the combustible compound reacting to give incombustible substance. The energy released will be -1268 kJ.
The combustible compounds and substances react in the presence of oxygen to give the incombustible compound are called the heat of combustion.
The reaction can be shown as:
[tex]\rm 2C_{6}H_{6}(g) + 15O_{2}(g) \rightarrow 12CO_{2}(g) + 6H_{2}O(g)[/tex]
We know that the molar enthalpy of combustion of benzene [tex](\rm C_{6}H_{6})[/tex] = -3170 kJ/mol
From the equation above,
1 mole of benzene [tex](\rm C_{6}H_{6})[/tex] undergoing combustion = -3170 kJ/mol
So, 0.4 moles of benzene = X energy
Solving for X:
[tex]\begin{aligned}\rm X &= 0.4 \times -3170\;\rm kJ\\\\&= -1268\;\rm kJ\end{aligned}[/tex]
Therefore, -1268 kJ of energy will be released.
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