Heat Capacity and Specific Heat in Thermodynamics

Thermodynamics is a branch of physics and chemistry that studies the relationships between function, heat, and temperature, as well as how they interact with radiation, electricity, and matter physical properties.

Thermodynamics is used in physical chemistry, biochemistry, chemical engineering, and mechanical engineering, as well as more sophisticated domains like meteorology.

Thermodynamics research

The study of the relationship between heat, work, temperature, and energy is known as thermodynamics. Thermodynamics, in its broadest definition, is concerned with the transition of energy from one location to another and from one sort to another. The three laws of thermodynamics, which provide a quantitative definition using observable macroscopic physical quantities but can be explained in terms of tiny constituents by statistical mechanics, regulate the behaviour of these values.

The fundamental theorem of thermodynamics, generally known as the law of energy conservation. The difference in internal energy of a system is the difference between heat added to the system from its surroundings and work done by the system on its surroundings.

The second law of thermodynamics explains how heat is transferred from one place to another. Heat does not naturally transfer from a cooler to a hotter environment, or, to put it another way, heat at a specific temperature cannot be converted to function completely.

The Third Law of Thermodynamics is one of the most important concepts in thermodynamics.

When the temperature reaches absolute zero, the entropy of a perfect crystal of an atom in its most stable state tends to zero.

This article will cover the topics of thermodynamics, heat capacity, and internal energy.

Thermodynamics’ Internal Energy

Internal energy refers to the energy stored within a thermodynamic device.

It refers to the amount of energy expended to build or plan a structure in any particular internal state. It eliminates the kinetic energy of the system’s overall motion, as well as the system’s overall potential energy due to external force fields, which includes the energy of the system’s surroundings’ movement. It keeps track of the energy gains and losses the system experiences as a result of changes in its internal environment. The internal energy is calculated as the difference between a reference zero provided by a normal condition and the internal energy.

Internal energy is a wide quality that is difficult to quantify.

The thermodynamic processes that characterise internal energy are transfers of matter or energy as heat, as well as thermodynamic function. These processes are calculated using changes in the system’s many parameters, such as entropy, volume, and chemical composition.

In equation form, the internal energy formula is U = Q-W.

The change in the device’s internal energy formula U is represented by U. The net heat transferred into the system is Q, which is the sum of all heat flows into and out of the system. W stands for the system’s network, or the total amount of work done on or by the system. The internal energy equation is used to determine how much a gas’s internal energy changes.

U = Q-W is the internal energy equation in thermodynamics, also known as the first law of thermodynamics.

A closed thermodynamic system’s internal energy.

Only the internal energy is an exact differential, but the differentials of each expression can be utilised to illustrate this relationship in infinitesimal terms.

For a closed system with solely heat and work transfers, the change in internal energy is

U = Q – W 

This is how the first law of thermodynamics is expressed.

It should be expressed using other thermodynamic parameters. Each word is made up of an intensive variable (a generalised force) and a conjugate infinitesimal extensive variable (a generalised displacement).

The pressure P and volume shift V, for example, can be linked to the mechanical work performed by the machine. The pressure is the intense generalised force, while the volume shift is the considerable generalised displacement:

W = PδV

A positive word indicates that the direction of work W is energy transfer from the working device to the surroundings.

Assuming that heat transfer Q is into the working fluid and that the process is reversible, the heat is,

δQ = TδS

The temperature is denoted by the letter T in the equation.

The entropy is denoted by the letter S in the equation.

As a result, the internal energy formula thermodynamics has changed.

δU = TδS – PδV 

Thermodynamics’ Heat Capacity

The amount of heat required to generate a unit change in temperature in a given mass of a substance is defined as heat capacity, also known as thermal capacity.

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The phrase “heat capacity” can refer to a variety of properties. The intense property that corresponds is the basic heat potential. Divide the heat capacity by the volume of a substance in moles to get the molar heat capacity. The volumetric heat capacity is used to calculate the heat capacity per volume. The term “thermal mass” is used in architecture and structural engineering to characterise a building’s thermodynamic heat capacity.

At constant pressure, heat supplied to the device contributes to both the work done and the change in internal energy, according to the first rule of thermodynamics.

The letter Cp denotes the heat capacity.

dV = 0, dQ = dU, heat capacity at constant volume (isochoric process)

The heat that was provided In thermodynamics, heat capacity is an object denoted by Q, hence the heat capacity equation is as follows:

C = ΔQ/ΔT

Where,

C: Capacity to generate heat

Q: What is total energy?

T: Temperature variation

Heat capacity of a homogeneous system subjected to different thermodynamic processes.

dQ = dU + PdV, heat capacity at constant pressure (Isobaric process)

Conclusion

We can explain the unique characteristics of water. Why water has such a high specific heat can be explained in part by the hydrogen bonding that occurs between molecules. Because of the multiple hydrogen bonds that connect the molecules, the molecules must vibrate in order to raise the temperature of the water. Because there are so many hydrogen bonds between water molecules, it takes more energy to cause the water molecules to vibrate and break apart.

Additionally, cooling down the temperature of water after being heated takes time. As heat is evacuated from the body, the temperature drops and the vibrational activity of water molecules slows. Due to the heat released, the cooling effect of heat loss from the liquid water is more than compensated.