Q11 / 160 · AP EAMCET 2003 · Chemistry

When $10 \mathrm{~g}$ of methane is completely burnt in oxygen, the heat evolved is $560 \mathrm{~kJ}$. What is the heat of combustion (in $\mathrm{kJ} \mathrm{mol}^{-1}$ ) of methane?

  • A
    -1120
  • B
    -968
  • Correct answer
    C
    -896
  • D
    -560

Solution

$\mathrm{CH}_4+2 \mathrm{O}_2 \longrightarrow \mathrm{CO}_2+2 \mathrm{H}_2 \mathrm{O}$ $10 \mathrm{~g} \Delta H=-560 \mathrm{~kJ}$ $(12+4=16) g=1 \mathrm{~mole}$ The heat of combustion of $10 \mathrm{~g} \mathrm{CH}_4=-560 \mathrm{~kJ}$ So, the heat of combustion of $16 \mathrm{~g} \mathrm{CH}_4$ $=\frac{-560}{10} \times 16=-896 \mathrm{~kJ} / \mathrm{mol}$

Hence, the correct answer is option: 'C'.

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