Question

Balance the following reaction and use the equation to calculate the ΔHrxn. C3H8(g) + O2(g) → CO2(g) + H2O(g) Round your answer to the nearest whole number. ΔHrxn=kJ/mole

Answer 1

The reaction corresponds to the combustion of propane (C3H8). The balanced reaction is:

C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)

The reaction enthalpy is given as:

ΔHrxn = ∑nΔH°f(products) - ∑ nΔH°f(reactants)

          = [3ΔH°f(CO2(g)) + 4ΔH°f(H2O(g)] - [1ΔH°f(C3H8(g)) + 5ΔH°f(O2(g)]

          = [3(-393.5) + 4(-241.8)] - [-103.9 + 5(0)] = -2043.8 kJ

The enthalpy for the combustion of propane is -2044 kJ