Question

In the combustion of $4g$. of ${CH}_4$,$2.5K$ cal of heat is if liberated. The heat of combustion of ${CH}_4$ is ?

• A. $20K$. cals
• B. $10K$. cals
• C. $2.5K$. cals
• D. $5K$. cals

Answer 1

Answer: (B)

$10K$. cals

$4g$ of ${CH}_4=\frac{4}{16}$ moles

$\frac{4}{16}$ moles liberates $2.5Kcal$ of heat

$\therefore 1$ mole liberates $\frac{2.5\times 16}{4}Kcal$ of heat

$=10Kcal$ of heat

Heat of Combustion is the heat liberated on complete combustion of $1$ mole of substance.

$\therefore$ Heat of combustion of ${CH}_4=10Kcal$