Question

The enthalpy of combustion of methane at ${25}^{\circ }C$ is $890$ kJ. The heat liberated when $3.2$ g of methane is burnt in air is:

• A. $445$ kJ
• B. $278$ kJ
• C. $-890$ kJ
• D. $178$ kJ

Answer 1

The correct option is D $178$ kJ

Number of moles of methane burnt $=\frac{3.2}{16}=0.2$

Enthalpy of combustion of 1 mole $=890$ kJ/mol

Heat liberated = $890\times 0.2=178$ kJ

Hence, option D is correct.