Nitric oxide reacts with oxygen to form nitrogen dioxide:

CHEMISTRY · Multi-part · A Level · Chemistry · Energetics · Energetics

Problem

Nitric oxide reacts with oxygen to form nitrogen dioxide: 2 NO(g)+O2(g)→2 NO2(g)\mathrm{2\,NO(g) + O_2(g) \rightarrow 2\,NO_2(g)}. A data booklet lists the following information: • Energy associated with forming 2.00 mol2.00\,\text{mol} of NO(g)\mathrm{NO(g)} from its elements: 180.5 kJ180.5\,\text{kJ} • Standard enthalpy of formation of NO2(g)\mathrm{NO_2(g)}: −66.0 kJ mol−1-66.0\,\text{kJ\,mol}^{-1} All values refer to standard conditions. (a) Convert the energy given for NO(g)\mathrm{NO(g)} to a molar standard enthalpy of formation, in kJ mol−1\text{kJ\,mol}^{-1}. (b) Using only the information provided, calculate the standard enthalpy change, in kJ, for the reaction as written. (c) Express the enthalpy change from part (b) on a per-gram basis for NO2(g)\mathrm{NO_2(g)} produced. Show all calculations. (d) Interpret the sign of your answer in part (b) in terms of the relative stability of reactants and products.

Related theory

Browse the problem library