The enthalpy changes for two reactions are listed below

CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics

Problem

The enthalpy changes for two reactions are listed below. 1) 12 N2(g)+12 O2(g)→NO(g)ΔH1=+90.2 kJ\tfrac12\,\mathrm{N_2}(g)+\tfrac12\,\mathrm{O_2}(g)\rightarrow\mathrm{NO}(g)\qquad \Delta H_1=+90.2\ \text{kJ} 2) NO(g)+12 O2(g)→NO2(g)ΔH2=−57.0 kJ\mathrm{NO}(g)+\tfrac12\,\mathrm{O_2}(g)\rightarrow\mathrm{NO_2}(g)\qquad \Delta H_2=-57.0\ \text{kJ} What is ΔH\Delta H for the reaction N2(g)+2 O2(g)→2 NO2(g)\mathrm{N_2}(g)+2\,\mathrm{O_2}(g)\rightarrow2\,\mathrm{NO_2}(g)? (a) +123.4 kJ+123.4\ \text{kJ} (b) +66.4 kJ+66.4\ \text{kJ} (c) −66.4 kJ-66.4\ \text{kJ} (d) +33.2 kJ+33.2\ \text{kJ}

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