Question

Thermal Energy needed to convert solid to liquid

• A. Melting point
• B. Sublimation heat
• C. Heat of fusion
• D. Latent heat

Hint:

Remember that heat of fusion is specific to the substance being melted and occurs at the substance's melting point.

Answer 1

The Correct Option is C

The question asks for the term used to describe the thermal energy needed to convert a solid into a liquid. This is a fundamental concept in thermodynamics and is crucial in the study of phase changes.

To determine the correct term, let's examine each option:

1. Melting point: This is the temperature at which a solid changes into a liquid. It is not the term for the energy required but rather a temperature measure.
2. Sublimation heat: This refers to the heat required to change a solid directly into a gas, bypassing the liquid phase, which is not applicable here.
3. Heat of fusion: This is the correct term. It refers to the amount of energy required to change a unit mass of a solid into a liquid without changing its temperature. It essentially breaks the bonds that hold the solid together, allowing it to become a liquid.
4. Latent heat: This is a general term used for the heat required to change the phase of a substance, such as solid to liquid or liquid to gas, without changing its temperature. While it is related, it does not specifically refer to the solid to liquid transition like the heat of fusion does.

Hence, the correct answer is Heat of fusion, as it specifically describes the thermal energy needed to convert a solid to a liquid without a change in temperature. This energy overcomes the molecular forces holding the solid structure together.

In formula terms, the heat of fusion (\(Q\)) can be calculated using:

Q = mL_f

where \(m\) is the mass of the substance and \(L_f\) is the heat of fusion or latent heat of fusion constant.