Question

Amount of heat required to change unit mass of substance from one phase to another phase is known as:

• A. Specific heat
• B. Entropy
• C. Latent heat
• D. Enthalpy

Hint:

Remember: latent heat is "hidden" heat.
During phase change, temperature remains constant.
Examples: melting ice (latent heat of fusion) and boiling water (latent heat of vaporization).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Phase change (e.g., solid to liquid, liquid to gas) requires heat energy.
This heat does not change the temperature of the substance but changes its phase.

Step 2: Key Formula or Approach:
Latent heat is the heat required for phase change.
Latent heat of fusion for solid to liquid.
Latent heat of vaporization for liquid to gas.

Step 3: Detailed Explanation:
Specific heat is the heat required to raise the temperature of unit mass by 1°C.
Entropy is a measure of disorder or randomness.
Enthalpy is the total heat content of a system.
Latent heat is specifically the heat required for a phase change without temperature change.
Thus, the correct answer is latent heat.

Step 4: Final Answer:
The amount of heat required to change the phase of unit mass of a substance is latent heat.
Hence, the correct option is (C).