Question

During the phase change, when water freezes it's converted to ice in which molecules are in a more structured order. Why does not this contradict the second law of thermodynamics?
A- because the density of the water is decreasing
B- because the water is gaining entropy as it goes from liquid to solid-state
C- Because the water’s internal energy is decreasing
D- Because the surroundings are losing entropy
E- Because the surrounding is gaining entropy

Answer 1

Hint: Phase change occurs because of the lowering of the temperature. Entropy is the function of the condition of the substance and thus it becomes a physical property of the substance. During the phase change from water to ice, the randomness decreases.

Complete step by step answer:
The change of phase from water to ice can never take place on its own either the temperature should go down or work has to be done on the system. The second law of thermodynamics states that heat can never move from a body at a lower temperature to a body at a higher temperature at its own. Now to change the state of water to solid-state, energy has to be removed from it and this energy goes to the surrounding which in turn increases the energy of the system. Thus, the entropy of water decreases and at the same time entropy of surrounding increases.

So, the correct answer is “Option E”.

Note:
Entropy of the universe is always increasing, and if the entropy of the universe becomes zero then the universe will die out ultimately. When heat is removed, the entropy decreases, when the heat is added the entropy increases.