A \(75 g\) ice cube at \(0^{\circ} C\) is placed in \(825 g\) of water at 25 \({ }^{\circ} C\). What is the final temperature of the mixture? [S.L.H ice \(=3.33 \times 10^{5} J / kg\), S.H.C water \(\left.=4200 J / kgk \right] .
A. \cdot 10^{\circ} C\) B. \(12^{\circ} C\) C. \(15^{\circ} C\) D. \(16^{\circ} C\)
Correct Answer: D
Explanation
Analysis: if there is no heat loss, then heat loss by water at \(25^{\circ} C\) to a final temperature \(\theta_{f}=\) heat gained by ice at \(0^{\circ} C\) plus water from \({ }^{\circ} C\) to a final temperature \(\theta_{f}\) \(\Longrightarrow(m c \Delta \theta)_{w}=\left(m l_{f}\right)_{\text {ice }}+(m c \Delta \theta)_{w}\) \(0.825 \times 4200 \times(25-\theta)\) \(=0.075 \times 333000+0.075 \times 4200 \times\left(\theta_{f}-0\right)\) \(=86625-3465 \theta_{f}=24975+315 \theta_{f}\) \(=315 \theta_{f}+3465 \theta_{f}=86625-24975\) \(=3780 \theta_{f}=61650\) \(\theta_{f}=\frac{61650}{3780}=16.3^{\circ} C\)