Thermal Equilibrium Related To Thermodynamics

Thermodynamics can be defined as a science platform reflecting a harmonious relationship between work, heat, energy, and temperature. In its broadest sense, thermodynamics is not only primarily associated with the transmission of energy from one object to another but the transformation from one form to another.

When we talk about heat, it was not formally recognized as a type of energy until around 1798 a British military engineer, Count Rumford found that infinite heat could be generated while boring cannon barrels. He also discovered that the amount of generated heat is proportional to the work done. It was due to Rumford’s observation that the relationship between heat and work exists at the heart of thermodynamics today.

Let’s discuss now what exactly is thermal equilibrium and the relationship between thermal equilibrium and thermodynamics.

What Is Thermal Equilibrium?

Some physics topics are intuitively understood by people before they’ve even heard of them. Thermal equilibrium, for example, is so important in our lives that we tend to understand it intuitively.

Take, for example, a hot mug of tea that you put in the freezer. So, what’s going to happen to the tea? The tea will cool down. That is common knowledge. You’re undoubtedly also aware that the tea will continue to chill until it reaches the same temperature as the freezer – or until it is solidly frozen and cannot be cooled anymore. Even if you’ve heard of this notion before, you might not realise that it’s a great example of thermal equilibrium.

Thermal equilibrium is the state in which no heat is transferred between two objects separated by a permeable barrier. When the temperature of two items is the same, thermal equilibrium happens.

Equation

When an object (or a system) is in thermodynamic equilibrium, the system’s thermodynamic potential has been minimised. The object will also be in thermal equilibrium if it is in thermodynamic equilibrium. The Helmholtz free energy, which represents the entire amount of usable work that might be collected from the system, is one of many types of thermodynamic potentials mentioned in physics. The Helmholtz free energy equation is as follows:

A = U – TS,

Where A = Helmholtz Free Energy (Joules, J)

U = Internal Energy (Joules, J)

T = Temperature (Kelvin, K)

S = Entropy (J/K)

This number will be at its lowest possible value if the system has reached thermodynamic equilibrium, as previously stated.

Example Usage Of Thermal Equilibrium

Below are some of the most important example usages of thermal equilibrium:

• Thermometer: The thermometer is put against the patient’s skin. When both the patient’s body temperature and the mercury (or alcohol) in the clinical thermometer have reached thermal equilibrium, the thermometer’s temperature is the same as the body temperature, and the thermometer’s reading reflects the patient’s body temperature.

• Refrigerator: When food is placed in the refrigerator, heat is transferred from the food to the refrigerator’s air. This process is repeated until the temperature of the food matches the temperature of the air in the refrigerator, indicating that the food and refrigerator have attained thermal equilibrium.

• Oven: When you place food in the oven, such as meat or cake, the heat from the oven is transferred to the food. This procedure will continue until the food and the air in the oven are in thermal equilibrium.

• Glaciers: Glaciers in the oceans and at the poles are examples of thermal equilibrium in action. Specifically, global warming warnings are linked to an increase in the temperature of the seas, followed by a thermal equilibrium in which much of the ice melts.

• Ice Cubes: A thermal equilibrium is achieved when an ice cube is placed in a glass of water. The only distinction is that equilibrium necessitates a state change since water transitions from solid to liquid at a temperature of 100 degrees Celsius.

Relationship Between Thermal Equilibrium And Thermodynamics

The average kinetic energy or movement of the molecules in a substance is defined as temperature. When two items of differing temperatures are brought into touch, the faster-moving molecules in one collide with the slower-moving molecules in the other. The heat energy will progressively dissipate until the two items attain thermal equilibrium, at which point they will be at the same temperature. This is similar to the second law of thermodynamics, which stipulates that heat only goes from hotter to colder areas spontaneously, never the other way around. This clearly shows one aspect of the relationship between thermal equilibrium and thermodynamics.

Moreover, the Zeroth Law of Thermodynamics underpins the concept of thermal equilibrium. When two systems are in thermal equilibrium with one another and a third system is in thermal equilibrium with the first system separately, the third system will be in thermal equilibrium with the second system. The Zeroth law of thermodynamics is a statement of this transitivity.

Consider two substances in thermal equilibrium, X and Y. Both X and Z will be in thermal equilibrium with one other if another body Z is in thermal equilibrium with Y. As a result, all of the bodies will be in thermal equilibrium with one another, and the temperatures of X, Y, and Z will be the same. Consequently, there will be no heat transmission and the system will be in thermal equilibrium.

When discussing the relationship between thermal equilibrium and thermodynamics, we can say that thermal equilibrium is a subset of thermodynamic equilibrium that focuses solely on the exchange of heat between two systems or between the system and the environment, even when there is no direct thermal energy transfer. On the other hand, physical, chemical, and thermal equilibrium are all addressed in thermodynamic equilibrium.

Conclusion

We learned that the state in which two things in physical contact do not exchange any heat energy is known as thermal equilibrium. The temperature of two substances in thermal equilibrium is said to be the same. Moreover, we also become aware of the Zeroth law of thermodynamics, which shows how objects at the same temperature lie in thermal equilibrium, and the overall heat exchanged between the objects becomes zero.

The Zeroth rule can be considered ex post facto because it provides a thermodynamic explanation for the function of thermometers and temperature scales that had been created prior to the law’s formulation.