✔ 最佳答案
1. Heat given out by water when its temperature falls to 0 deg.C
= 1 x 4200 x 20 J = 84000 J
Heat absorbed by ice if it melts completely = 0.5x 334000 J = 167000 J
where 334000 J/kg is the latent heat of fusion of water
Since the heat given out by the water is not sufficient to melt all the ice, the final temperature is still at 0 deg.C with water and ice in equilibrium.
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2. Energy given out by the heater in 3 minutes = 10 x 3 x 60 J = 1800 J
The heat is absorbed by 10/1000 kg of liquid to become vapour.
thus latent heat of vapourization = Heat absorbed/mass of lquid
= 1800/0.01 J/kg = 180 000 J/kg
