Question

Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reaction: 4 NO(g) + 2 O₂(g) → 4 NO₂(g).

Answer 1

The standard reaction enthalpy (ΔH°rxn) for the reaction 4 NO(g) + 2 O2(g) → 4 NO2(g) is calculated by doubling the provided reaction enthalpy of 2 NO(g) + O2(g) → 2 NO2(g), yielding a ΔH°rxn of -228.2 kJ.

Step-by-step explanation:

To calculate the standard reaction enthalpy (ΔH°rxn) for the reaction 4 NO(g) + 2 O2(g) → 4 NO2(g), we must use the provided standard reaction enthalpies. We have the following individual reactions and their standard enthalpies (ΔH°):

• 2NO(g) + O2(g) → 2NO2(g), ΔH° = -114.1 kJ

To get the enthalpy change for 4 moles of NO reacting, we need to double this reaction and its enthalpy change:

• 4NO(g) + 2O2(g) → 4NO2(g), ΔH° = 2 (-114.1 kJ) = -228.2 kJ

Therefore, the standard reaction enthalpy for the given reaction is -228.2 kJ.