Difference Between Latent Heat and Sensible Heat

Main Difference – Latent Heat vs Sensible Heat

Latent heat and sensible heat are two forms of energy that are used in explaining the relationship between the temperature and matter. These terms have many applications in our day to day life. The latent heat is the transfer of energy from or to a system during a phase transition of matter. The sensible heat is the exchange of energy between the system and the surrounding which cause some macroscopic features to change while other macroscopic features remain constant. The main difference between latent heat and sensible heat is that latent heat is defined for a system that undergoes a phase change of matter whereas sensible heat is defined for a system that has no change in the phase of matter.

Key Areas Covered

1. What is Latent Heat
      – Definition, Different Types of Latent Heat
2. What is Sensible Heat
      – Definition, Usage of the Term
3. What is the Difference Between Latent Heat and Sensible Heat
      – Comparison of Key Differences

Key Terms: Latent Heat, Macroscopic Features, Phase Transition, Sensible Heat, Thermodynamic System

What is Latent Heat

Latent heat is the amount of energy that is either absorbed or released during a phase transition at a constant temperature. Phase of matter is the form of matter that has uniform chemical and physical properties all over the substance that is considered. Changing this phase of matter is known as a phase transition. Here, the new phase also should have the uniformity of properties. When the phase of matter is changed, it either requires energy or releases energy in the form of heat. This exchanged energy is called latent heat.   

The three main phases of matter are solid phase, liquid phase and gas phase. The value of latent heat varies with the nature of matter. Given below are examples.

• When a liquid is converted into its solid phase, it is known as the latent heat of fusion.
• When a liquid is converted into its gaseous phase, it is known as the latent heat of vaporization.
• When a solid is converted into its gaseous phase, it is known as the latent heat of sublimation.

Figure 1: Phase Transition of Matter

Latent heat is defined for a system with constant temperature. Therefore, this term describes the change of phase regarding the internal energy of the system. Latent heat is the work done in a system in order to hold the atoms or molecules of matter in the same phase.

What is Sensible Heat

Sensible heat is the energy required to change the temperature of a substance with no phase change. In other words, sensible heat is the heat that can be felt. It is a type of energy that is either absorbed or released by a system. The changes in the temperature of systems cause changes in the sensible heat. Unlike in latent heat, there is no change in phase of matter in the system when considering the sensible heat. It only describes the change in the temperature.

Figure 2: Air conditioners work with the help of sensible heat

For example, boiled water feels warmer than cold water. This difference can be observed due to the sensible heat. In air conditioners, the cooling liquid or the refrigerant changes its temperature according to the sensible heat.

Difference Between Latent Heat and Sensible Heat

Definition

Latent Heat: Latent heat is the amount of energy that is either absorbed or released during a phase transition at a constant temperature.

Sensible Heat: Sensible heat is the energy required to change the temperature of a substance with no phase change.

Phase Transition

Latent Heat: Latent heat is defined for a system with phase transition.

Sensible Heat: Sensible heat is defined for a system without phase transition.

Energy Exchange

Latent Heat: Latent heat describes the changes in the internal energy of matter.

Sensible Heat: Sensible heat describes the energy exchange between matter and surroundings.

Change in Macroscopic Properties

Latent Heat: Latent heat is related to a system at a constant temperature.

Sensible Heat: Sensible heat is related to a system with changes in temperature.

Conclusion

Latent heat and sensible heat are two forms of energy. Latent heat describes the changes in the internal energy of a system whereas sensible energy describes the energy exchange between a system and its surrounding. The main difference between latent heat and sensible heat is that latent heat is defined for a system that undergoes a phase change of matter whereas the sensible heat is defined for a system that has no change in the phase of matter.

References:

1. “Latent heat.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 12 Oct. 2016, Available here.
2. “Latent Heat: Definition, Formula & Examples.” Study.com, Available here.
3. “Sensible heat.” Sensible heat – Energy Education, Available here.

Image Courtesy:

1. “Toshiba Daiseikai Air Conditioner” By Santeri Viinamäki (CC BY 4.0) via Commons Wikimedia