Question

The molar heat capacity $\left(C_p\right)$ of water at constant pressure is $75J{K}^{-1}{mol}^{-1}$. The increase in temperature (in $K$) of $100g$ of water when $1kJ$ of heat is supplied to it is:

• A. $2.4$
• B. $0.24$
• C. $1.3$
• D. $0.13$

Answer 1

The correct option is A $2.4$

Molar heat capacity $=75J{K}^{-1}mo{l}^{-1}$

$18g$ of water $=1$ mole $=75J{K}^{-1}mo{l}^{-1}$

$1g$ of water $=\frac{75}{18}J{K}^{-1}{g}^{-1}$

$Q=m.C.\Delta T$ "or" $1000=100\times \frac{75}{18}\times \Delta T$

$\Rightarrow \Delta t=\frac{10\times 18}{75}=2.4K$