A
mixture of 1.78 kg of
water and 262 g of ice
at
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Solution: Click For PDF Version (a)
Amount of
water present,
Amount of ice
present,
Therefore,
Amount of water that will have to be freezed for water and ice to become 1:1 by mass,
Heat of
fusion of water,
The amount of
heat to be added to the mixture of ice and water for freezing 0.759
kg of water into ice at
That is
The entropy of the system has decreased as water has been transformed into a more ordered crystalline state. (b) Now when 0.759 kg of ice is melted by adding heat using say a Bunsen burner, the thermodynamic process is irreversible. The amount of heat to be added to the system for bringing the system back into its initial state will also be 252.7 kJ. And the change in entropy ( by using a reversible path connecting the two states) will be
The statement of the second law of thermodynamics is that in any thermodynamic process that proceeds from one equilibrium state to another, the entropy of the system plus that of the environment either remains unchanged or increases. The change in entropy that we have worked out is not the total change of entropy of the system and that of the environment taken together. Therefore, there is no inconsistency with the second law of thermodynamics. |
is,
in a reversible process, brought to a final
equilibrium state where the water ice/ratio,
by mass is 1:1 at
of heat will have to be extracted from the ice-water mixture so that
the ratio of ice to water becomes 1:1. The change in the entropy of
the system will be
