Combustion of methane proceeds according to CH _4(g)+2 , O _2(g) CO _2(g)+2 , H _2 O (l)

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

Problem

Combustion of methane proceeds according to

\text{CH}_4(g)+2\,\text{O}_2(g)\longrightarrow \text{CO}_2(g)+2\,\text{H}_2\text{O}(l).

The measured enthalpy change for one mole of

\text{CH}_4

combusted is

\!-890\,\text{kJ}

. Given

\Delta H_f^\circ[\text{CO}_2(g)]= -393.5\,\text{kJ}\,\text{mol}^{-1}

and

\Delta H_f^\circ[\text{H}_2\text{O}(l)]= -285.8\,\text{kJ}\,\text{mol}^{-1}

, which value is closest to

\Delta H_f^\circ[\text{CH}_4(g)]

? (a)

+1.85\times10^{2}\,\text{kJ}\,\text{mol}^{-1}

(b)

-2.86\times10^{2}\,\text{kJ}\,\text{mol}^{-1}

(c)

-7.5\times10^{1}\,\text{kJ}\,\text{mol}^{-1}

(d)

+7.5\times10^{1}\,\text{kJ}\,\text{mol}^{-1}