Question

The enthalpy of formation of nitrogen dioxide is +33.2 kJ mol⁻¹. The enthalpy of the reaction \[\ce{2N2_{(g)} + 4O2_{(g)} -> 4NO2_{(g)}}\]; is ____________.

Options

• −33.2 kJ

• +33.2 kJ

• −66.4 kJ

• +132.8 kJ

Answer 1

The enthalpy of formation of nitrogen dioxide is +33.2 kJ mol⁻¹. The enthalpy of the reaction \[\ce{2N2_{(g)} + 4O2_{(g)} -> 4NO2_{(g)}}\]; is +132.8 kJ.

Explanation:

∆_fH refers to the formation of one mole of NO₂.

i.e. \[\ce{1/2 N2_{(g)} + O2_{(g)} -> NO2_{(g)}}\]; ∆_fH = +33.2 kJ

∴ ∆H for 4 moles = 4 mol × 33.2 kJ = +132.8 kJ.

∴ Enthalpy of the given reaction is +132.8 kJ