Question

$2kg$ of ice at $-{20}^{\circ }C$ is mixed with 5 kg of $H_{2}O$ at ${20}^{\circ }C$ in an insulating vessel having negligible heat capacity. Calculate the final mass of water left in the container.
Given: specific heats of water and ice are $1kcalk{g}^{-1\circ }{C}^{-1}$
and $0.5kcalk{g}^{-1\circ }{C}^{-1}$ and latent heat of fusion of ice is $80kcalk{g}^{-1}$.

• A. 7 kg
• B. 6 kg
• C. 4 kg
• D. 2 kg

Answer 1

The correct option is B 6 kg

$m_{ice}^{\prime }L+m_{ice}20\left(0.5\right)=m_W\left(1\right)\left(20\right)$

$m_{ice}^{\prime }80=5\times 20-2\times \left(20\right)\times 0.5=80$

$\therefore m_{ice}^{\prime }=1kg$

Hence total amount of water = $6kg$.