The Enthalpy of Combustion of Butane

Introduction

Butane (C₄H₁₀) combusts in the presence of oxygen to form carbon dioxide (CO₂) and water (H₂O). The enthalpy of combustion for butane can be calculated using the given heat of formation values.

Calculating Enthalpy of Combustion

Given:

Heat of formation of C₄H₁₀ = -125.7 kJ/mol

Heat of formation of water = -241.82 kJ/mol

Heat of formation of CO₂ = -393.5 kJ/mol

Using the formula:

ΔH = ∑H_products - ∑H_reactants

ΔH = 8(-393.5) + 10(-241.82) - 2(-125.7)

ΔH = -5314.8 kJ/mol

This energy would result in the combustion of 2 moles of butane. Therefore, energy required for the combustion of 1 mole of butane is:

-2657.4 kJ/mol

How is the enthalpy of combustion of butane calculated?

The enthalpy of combustion of butane is calculated by subtracting the sum of the heat of formation of reactants from the sum of the heat of formation of products. In this case, the enthalpy of combustion value is -2657.4 kJ/mol.