Question

Calculate the enthalpy of combustion of butane, C₄H₁₀(g) for the formation of H₂O(g) and CO₂(g). The enthalpy of formation of butane is −126 kJ/mol.

Answer 1

The enthalpy of combustion of butane for the formation of H₂O and CO₂ is 948 kJ/mol.

Step-by-step explanation:

The enthalpy of combustion can be calculated by subtracting the enthalpy of formation of the reactants from the enthalpy of formation of the products. In this case, we need to calculate the enthalpy of combustion of butane, C4H10(g), for the formation of H2O(g) and CO2(g). The enthalpy of formation of butane is -126 kJ/mol. The enthalpy of formation of H2O(g) is -286 kJ/mol and the enthalpy of formation of CO2(g) is -394 kJ/mol.

To calculate the enthalpy of combustion, the enthalpy change of formation for butane is multiplied by the stoichiometric coefficient of butane, which is 1. The enthalpy change of formation for H2O(g) is multiplied by the stoichiometric coefficient of H2O(g), which is -1 since it is a product. The enthalpy change of formation for CO2(g) is multiplied by the stoichiometric coefficient of CO2(g), which is -2 since it is a product. The enthalpy of combustion is then calculated as follows:

(-126 kJ/mol * 1) + (-286 kJ/mol * -1) + (-394 kJ/mol * -2) = -126 kJ/mol + 286 kJ/mol + 788 kJ/mol = 948 kJ/mol