The amount of heat required for converting one kilogram of a solid completely into liquid is called:
Latent heat of fusion
Heat for Converting Solid to Liquid: Understanding Latent Heat of Fusion
When a substance undergoes a change in its physical state, such as transforming from a solid to a liquid, it either absorbs or releases energy without a corresponding change in its temperature. This specific energy is commonly referred to as latent heat. The question focuses on the amount of heat required for converting one kilogram of a solid completely into liquid.
Latent Heat Explained
The term "latent" signifies something hidden or concealed. Latent heat is the energy that a substance absorbs or releases during a phase transition, while its temperature remains constant. Different types of phase changes are associated with distinct forms of latent heat:
- Latent Heat of Fusion: This is the precise amount of heat energy necessary to transform one kilogram of a solid substance into its liquid state at its melting point, with no change in temperature. This process is universally known as melting. The energy supplied is primarily used to break the intermolecular bonds that hold the solid structure together.
- Latent Heat of Vaporization (or Evaporation): This refers to the heat energy needed to convert one kilogram of a liquid substance into its gaseous state at its boiling point, without any alteration in temperature. This phenomenon is commonly called boiling or evaporation.
- Latent Heat of Sublimation: This is the heat energy required to directly convert one kilogram of a solid substance into its gaseous state, completely bypassing the liquid phase, all while maintaining a constant temperature.
Analyzing the Options for Solid to Liquid Conversion
Let's evaluate each given option to determine its relevance to the process of converting a solid into a liquid:
| Option | Description | Relevance to Converting Solid to Liquid |
|---|---|---|
| Specific heat | The quantity of heat energy needed to raise the temperature of one kilogram of a substance by one degree Celsius (or Kelvin) without causing a change in its physical state. | This concept applies to temperature changes within a single phase, not to phase transitions like solid to liquid conversion. Therefore, it is not the correct answer. |
| Latent heat of fusion | The exact amount of heat energy required to convert one kilogram of a solid entirely into a liquid at its melting point, without any accompanying temperature change. | This definition perfectly aligns with the scenario described in the question. It precisely describes the heat involved in the melting process. |
| Latent heat of sublimation | The heat energy required to convert one kilogram of a solid directly into a gas, bypassing the intermediate liquid state. | This is not applicable, as the question specifically states conversion into a liquid, not a gas. |
| Latent heat of evaporation | The heat energy needed to convert one kilogram of a liquid into a gas. | This is also not applicable because the starting state in the question is a solid, not a liquid, and the target state is liquid, not gas. |
Calculating Heat for Phase Change
The total heat energy (\( Q \)) involved in a phase change, such as the conversion of a solid to a liquid, for a given mass (\( m \)) of the substance can be calculated using the following fundamental formula:
\[ Q = m \times L \]
In this formula:
- \( Q \) represents the total heat energy that is either absorbed or released, typically measured in Joules (J).
- \( m \) denotes the mass of the substance undergoing the phase change, usually measured in kilograms (kg).
- \( L \) stands for the specific latent heat of the particular phase change, expressed in Joules per kilogram (\( J/kg \)). For the conversion of a solid to a liquid, \( L \) specifically refers to the latent heat of fusion.
Given that the question specifies "one kilogram" of the solid, the amount of heat required is numerically equal to the specific latent heat of fusion for that particular substance.
Conclusion on Heat for Solid to Liquid Conversion
Based on the scientific definitions and a thorough analysis of the options, the amount of heat required for converting one kilogram of a solid completely into liquid is accurately defined as the latent heat of fusion. This fundamental thermal property quantifies the energy input necessary for the melting process to occur.
Important Questions from The Perfect Gas
The quantity of heat required to raise the temperature of unit mass of a material by one degree centigrade is called
The heat that must be absorbed by ice of mass 500 g at – 10°C to take it to water at 20°C is (Specific heat of Ice is 2.2 kJ/kg K, Specific heat of water is 4.2 kJ/kg K and Latent heat of fusion of ice is 300 kJ/kg)
2 kg of substance receives 500 kJ and undergoes a temperature change from 100°C to 200°C. The average specific heat of substance during the process will be
The general law for the expansion or compression of gases is:
Amount of energy required to raise the temperature of a substance of 1 kg mass by 1°C is called
