Physics - Latent heat question
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Physics - Latent heat question

[From: ] [author: ] [Date: 13-03-13] [Hit: ]
the final temperature is 4.14*C. Find the mass of ice added.I got the answer of 0.103Kg but the proper answer is 0.655Kg.......
A thermally insulated glass of mass 435g contains 125g of water at a temperature of 45.4*C. When a lump of ice initially at -2.50*C is allowed to melt in the water, the final temperature is 4.14*C. Find the mass of ice added.
I got the answer of 0.103Kg but the proper answer is 0.655Kg.
Can anyone show the working out for this?

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Heat lost = Heat gained

Cp Water (Specific Heat) = 4.186kJ/kgC
Cp Glass = .84kJ/kgC
(d)T (change in temp) = (45.4C - 4.14) = 41.26C

Q (Heat) = Cp × m × (d)T
Q = (4.186kJ/kgC × .125kg × 41.26C)+(.84kJ/kgC × .435kg × 41.26C)
Q= 36.66 kJ = Heat Lost

Heat Gained:
Cp Ice = 2.05kJ/kgC
Heat of fusion water = 334kJ/kgC
Cp water = 4.186 kJ/kgC
Q = (2.05kJ/kgC × 2.5C × m) + (334kJ/kg ×m) + (4.186kJ/kgC × 4.14C × m)
Q = 5.125 kgm+ 334kJm + 17.33kJm = 356.45kJm

Heat Lost = Heat gained
36.66 kJ = 356.45Jm
m = 36.66/356.45 kg = .103kg

Check the initial data given.
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