A 100W heater is used melt 50g ice at 0°C. How long should the heater be switched on? (The specific latent heat of fusion of ice is 334 J/g)
Correct answer: C. 2.8 minutes
- A. 28 minutes
- B. 16.7 minutes
- C. 2.8 minutes
- D. 167 minutes
Explanation
Q = mLf; where Q is the heat supplied, m is mass of ice, and Lf is the specific latent heat of fusion of ice. So Q = 50 x 334 = 16,700 JPower = Energy/TimeTherefore, Time = E/P = 16700 / 100 = 167 seconds which is equal to 2.8 minutes. Hence, Option C is correct.
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