The combustion of 1 mole of octane,C₈H₁₈(l),to produce carbon dioxide and liquid water has $\Delta$H_r = -5471 kJ.mol^-1 at 298 K.What is the change in internal energy for this reaction?

Question

Quizplus · Accepted Answer

The change in internal energy ($\Delta U$) can be calculated using the relation $\Delta H = \Delta U + \Delta nRT$. For the combustion of octane, $\Delta n = -5$ (since 12 moles of gas are produced from 17 moles of gas). Using R = 8.314 J/mol·K and T = 298 K, $\Delta nRT$ is approximately -11 kJ/mol. Thus, $\Delta U = \Delta H - \Delta nRT = -5471 kJ/mol - (-11 kJ/mol) = -5460 kJ/mol$.

The Combustion of 1 Mole of Octane,C8H18(l),to Produce Carbon Dioxide Δ\DeltaΔ

The Combustion of 1 Mole of Octane,C₈H₁₈(l),to Produce Carbon Dioxide $\Delta$