Question

Ice cubes are added to an insulated cup of hot water. As a result, the temperature of the water decreases and the ice melts. What statement best explains the change in entropy of the system, which is the combination of water and ice cubes, on a molecular level?
a. The entropy of the system decreases, because the translational and vibrational motion of molecules in the liquid water decrease during collisions with molecules in the ice.
b. The entropy of the system remains unchanged, because the same amount of heating and cooling occur.
c. The entropy of the system increases, because the energy gained by the ice molecules is greater than the energy lost by the liquid water molecules.
d. The entropy of the system increases, because the disorder caused by the change in state from solid to liquid water causes more disorder than liquid water cooling causes order.

Answer 1

Answer:

d. The entropy of the system increases, because the disorder caused by the change in state from solid to liquid water causes more disorder than liquid water cooling causes order.

Explanation:

Entropy of a state may be defined as a natural process and spontaneous process. It is the measure of the disorder and randomness of the event.

In the context, when ice cubes are dropped in a cup of hot water which is insulated, the ice melts and the water temperature decreases. According to the principle of entropy increase, option A is wrong as the process in not a reversible process and option B is also wrong as it violates the principle of energy conservation. So option D is correct which shows the disorderness of the system.