Latent Heat

Definition

Latent heat refers to the energy released or absorbed by a substance during a phase change, such as the transition from a solid to a liquid or from a liquid to a gas, without a change in temperature. It is the energy required to change the state of a substance without altering its temperature.

5 Must Know Facts For Your Next Test

1. Latent heat is the energy required to change the state of a substance without changing its temperature.
2. During a phase change, the temperature of the substance remains constant while energy is absorbed or released.
3. The amount of latent heat required depends on the specific substance and the phase change involved.
4. Latent heat is an important concept in understanding heat transfer, specifically in processes like boiling, condensation, and melting.
5. Latent heat is a key factor in the design and operation of many engineering systems, such as refrigeration and air conditioning.

Review Questions

• Explain how latent heat is related to the concept of thermal equilibrium.
  • Latent heat is closely tied to the concept of thermal equilibrium. During a phase change, the temperature of a substance remains constant as energy is absorbed or released, allowing the system to maintain a state of thermal equilibrium. This is because the energy required to change the state of the substance is not used to raise or lower the temperature, but rather to overcome the intermolecular forces that hold the substance in its current state. As a result, the temperature remains constant until the phase change is complete, and the system can then proceed to change temperature again.
• Describe how latent heat is involved in the process of heat transfer, specifically in the context of calorimetry.
  • Latent heat plays a crucial role in the process of heat transfer, particularly in the context of calorimetry. When a substance undergoes a phase change, such as melting or boiling, it absorbs or releases a significant amount of energy in the form of latent heat. This energy is not used to change the temperature of the substance, but rather to overcome the intermolecular forces that hold the substance in its current state. In calorimetry experiments, the amount of latent heat involved in a phase change can be measured and used to determine the specific heat capacity or enthalpy of the substance, which are important parameters in understanding heat transfer processes.
• Analyze how the concept of latent heat is applied in the context of phase changes, and explain its importance in understanding the behavior of substances during these transitions.
  • The concept of latent heat is fundamental to understanding the behavior of substances during phase changes. When a substance undergoes a phase change, such as the transition from a solid to a liquid or a liquid to a gas, it absorbs or releases a significant amount of energy without a change in temperature. This latent heat is the energy required to overcome the intermolecular forces that hold the substance in its current state. The amount of latent heat involved in a phase change is a characteristic property of the substance and varies depending on the specific phase transition. Understanding latent heat is crucial in predicting and analyzing the behavior of substances during phase changes, which is essential in various applications, including refrigeration, air conditioning, and the design of thermal systems. By considering the latent heat associated with phase changes, we can better understand the energy requirements, efficiency, and limitations of these systems.

Related terms

Specific Heat:

The amount of energy required to raise the temperature of a substance by one degree Celsius or Kelvin, typically measured in Joules per kilogram-degree.

Phase Change:

The transition from one state of matter (solid, liquid, or gas) to another, which occurs at a specific temperature and pressure.

Enthalpy:

The total energy of a thermodynamic system, including its internal energy and the work done on or by the system.