Question

The heat of combustion of methane is $-800$ kJ. What is the heat of combustion for $4\times {10}^{-4}$kg of methane?

• A. $-800kJ$
• B. $-3.2\times {10}^{4}kJ$
• C. $-20kJ$
• D. $-1600kJ$

Answer 1

The correct option is C $-20kJ$

$\underset{16g}{C{H}_4}+2O_2\to C{O}_2+2H_{2}O;\Delta H_c=-800kJ$

$\because$ Heat of combustion of $16\times {10}^{-3}$ kg of $C{H}_4=-800kJ$

$\therefore$ Heat of combustion of $4\times {10}^{-4}$kg $C{H}_4$ will be $=-\frac{800\times 4\times {10}^{-4}}{16\times {10}^{-3}}=-20kJ$