Question

When $50g$ of water at $10^{\circ }C$ is mixed with $50g$ of water at $100^{\circ }C$, the resultant temperature is

• A. $80^{\circ }C$
• B. $55^{\circ }C$
• C. $25^{\circ }C$
• D. $45^{\circ }C$

Answer 1

Answer: (B)

If resulting temperature of the mixture is $T^{\circ }C$ then Heat gained by $50g$ water at $10^{\circ }C$,
$H_{\text{gain }}=mc\Delta T=50c(T-10)$
Heat lost by $50g$ of water at $100^{\circ }C$
$H_{\text{loss }}=mc\Delta T=50c(100-T)$
According to principle of calorimetry,
Heat gain $=$ Heat loss
$\Rightarrow H_{\text{gain }}=H_{\text{loss }}$
$\Rightarrow 50c(T-10)=50c(100-T)$
$\Rightarrow 2T=110$
$T=55^{\circ }C$