heat question

I presume that the initial temperature of ice is at 0'C (please check your question if this is given).

Heat released by 0.5 kg of ice on melting
= 0.5 x 3.34x10^5 J = 167 000 J

Heat absorbed by 1 kg water when its temperature drops to 0'C
= 1 x 4200 x 20 J
= 8 400 J

Hence, you can see that the heat released by water, when its temperature falls to 0'C, is NOT sufficient to melt all 0.5 kg ice. There is ice remaining in the mixture. That is, the final mixture is ice and water in equilibrium at 0'C.

In fact, you can calculate the amount of ice melted, which is
= 8400/3.34x10^5 kg = 0.0251 kg
Therefore, there remains (0.5 - 0.0251) kg = 0.475 kg of ice




2012-09-25 10:38:00 補充：
sorry...some typos.
The words "released" and "absorbed" in the 2nd and 3rd para. should be interchanged.