# Gibbs Free Energy For Combustion of Octane

Calculate delta G combustion at 25'C of octane, c8H18(l),

2C8H18(l) + 25 O2(g) -------> 16 CO2(g) + 18 H2O(l)

Using the following thermodynamic data and that given in textbook.

For C8H18(l), delta H formation = - 208.4 kJ mol-1 and delta S = 463.71 JK-1 mol-1. Give your answer in kJ mol-1 of C8H18 (l).

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#### Solution Preview

dH = [(16 x dHf CO2) + (18 x dHf H2O)] - [(2 x dHf C8H18) + (25 x dHf O2)]

dH = [(16 x -393.5) + ...

#### Solution Summary

The Gibbs free energy for combustion of octane is calculated.

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