What quantity of heat energy is required to completely evaporate \(1 \mathrm{~kg}\) of ice originally at \(0^{\circ} \mathrm{C}\) ? [Specific latent heat of fusion of ice \(3.35 \times 10^5 \mathrm{Jkg}\), specific latent heat of vaporization of water \(2.26 \times 10 \mathrm{Jkg}^{-1}\), specific heat of capacity of water \(4200 \mathrm{Jkg}^{-1} \mathrm{~K}^{-1} \mathrm{~J}\)
A. \(750 \mathrm{KkJ} \) B. \(3015 \mathrm{~kJ}\) C. \(4050 \mathrm{~kJ}\) D. \(5130 \mathrm{~kJ}\)
Correct Answer: B
Explanation
- To melt the ice at \(0^{\circ} \mathrm{C}\), the heat used is given as: \(Q_1-m l_f\) \(=\left(1 \times 3.35 \times 10^5\right) \mathrm{J}=3.35 \times 10^5 \mathrm{~J}\) - To raise the temperature of the water formed from \(0^{\circ} \mathrm{C}\) to \(100^{\circ} \mathrm{C}\), the heat used is given as: \begin{aligned} Q_2 &=m c \Delta \theta \\ &=1 \times 4200 \times(100-0) \\ &=4.2 \times 10^5 \mathrm{~J} \end{aligned} - To evaporate the water at \(100^{\circ} \mathrm{C}\), the heat used is given as
