Question

Melting point of ice.
A. Increase with increasing pressure
B. Decrease with increasing pressure
C. Is independent of pressure
D. Is proportional of pressure

Answer 1

Hint: Melting point is the temperature at which a material changes from solid state to liquid state. Ice is a solid form of water. We can solve this problem using the second law of thermodynamics and Le Chatelier’s principle, it states that when a system experiences a disturbance it will respond to restore a new equilibrium state.

Complete answer:
We can solve this question using Le Chatelier’s principle. It states that when a system is in equilibrium, when there are any external changes in the system that changes the state of equilibrium the system tries to counter such changes. As we know that due to inertia the system wants to remain in the same state.

A state of equilibrium means the system has achieved maximum entropy. This is why when there is some external disturbance, the system counter and the reason for this transition is change in temperature when pressure is applied to ice. For most of the systems, melting point increases with an increase in pressure except for water. This strange behavior of the water-ice system is observed because water expands when it freezes. This means that ice occupies more volume than water.

Let us see what happens when pressure is applied to such a system. As the pressure increases, the water-ice system tries to maintain its entropy by occupying a smaller volume and since water occupies less volume, more and more ice is converted into water which results in a decrease of melting point. This means that by applying pressure to ice its melting point will decrease.

Thus, option B is the correct option.

Note: The melting point is when the state of a substance changes from solid to liquid and boiling point is when the state changes from liquid to gas. Please note that transition temperature depends on the exchange change of the system. At zero-degree centigrade water is in the form of ice.