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A piece of copper of mass `m = 90 g` at a temperature `t_1 = 90 ^@C` was placed in a calorimeter in which ice of mass `50 g` was at a temperature `-3 ^@C`. Find the entropy increment of the piece of copper by the moment the thermal equilibrium is reached. |
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Answer» `c =` specific heat of copper `= 0.39 (J)/(g. K)` Suppose all ice does not melt, then heat rejected `= 90 xx 0.39 (90 - 0) = 3159 J` Heat gained by ice `= 50 xx 2.09 xx 3 + x xx 333` Thus `x = 8.5 gm` The hypothesis is correct and final temperature will be `T = 273 K` Hence change in entropy of copper piece =`mc 1n (273)/(363) = - 10 J//K`. |
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