Consider the following reactions at :

CHEMISTRY · Subjective · A Level · Chemistry · Thermodynamics · Thermodynamics

Problem

Consider the following reactions at

298\,\text{K}

: (i)

C(s,\ \text{graphite}) + \frac{1}{2}O_2(g) \rightarrow CO(g)

\Delta G^\circ_1 = ?

(ii)

CO(g) + \frac{1}{2}O_2(g) \rightarrow CO_2(g)

\Delta G^\circ_2 = -257.0\,\text{kJ}

(iii)

C(s,\ \text{graphite}) + O_2(g) \rightarrow CO_2(g)

\Delta G^\circ_3 = -394.4\,\text{kJ}

Using the data above, determine the standard Gibbs free energy of formation of

CO(g)

\text{kJ}\,\text{mol}^{-1}

. Report your answer to the nearest kilojoule.