HEAT WORK AND INTERNAL ENERGY

The form of energy that transfers from one system to another is called heat, and it does not depend on the system. But if the energy depends upon the system, it is termed internal energy. All heat work and internal energy are interrelated. Let us see in detail.

WHAT IS INTERNAL ENERGY?

• The energy present inside the system results from the random movements of the particles.
• The total energy present in the system K.E( energy due to random particle motion) and P.E(energy-related to particle) is called internal energy.
• For an ideal gas, the temperature is only the factor on which the internal energy depends
• For natural gas, both temperature and volume are needed for internal energy.
• The temperature may affect the point of departure and aperture in internal energy, but the path won’t be affected.
• U is the letter used to represent the internal energy, and the unit is Joule.

Here is the formula relating heat work and internal energy

ΔU =ΔQ – ΔW

ΔU represents a change in internal energy of the thermodynamics system

ΔW represents work done 

If we differentiate the above equation, we get dU = dQ – dW

RELATION BETWEEN ENTHALPY AND INTERNAL ENERGY

It is theoretically proven that ideal gas is purely dependent on temperature, not only theoretical but also it is proven mathematically. All heat, work, and internal energy are interrelated.

The U( internal energy) of the ideal gas is U=U(T)

H= U+ PV represents the enthalpy of the system

Where 

P – represent the pressure inside the body

V is the volume of the given ideal gas

Apply the ideal gas equation( PV= RT) in the above equation

Where R is the ideal gas constant and T is the temperature of an ideal gas

The enthalpy of the ideal gas equation is H = H(T)

We already know that the volume( Cv) and pressure(Cp) (specific heat) are temperature-dependent. where the equation is given by dU = Cv(T)dT,  dH= Cp(T)dT

• dT represents gas heated temperature(small)
• Cv represents, At constant volume, the molar specific heat capacity
• Cp represents, At constant pressure, the molar specific heat capacity

by using the above two equations in the specific heat ratio(k) is given as k= Cp/Cv= U/H

INTERNAL ENERGY ENTHALPY

Internal energy represents the total energy present in the system Enthalpy represents the relationship between the system and surroundings. Enthalpy is given by following equation: 

H= U+ PV

The energy present inside the system results from the random movements of the particles. As well as the P.E. (potential energy) of the molecules as a result of their orientation, such types of energy are called internal energy.

During a chemical reaction, the energy can either be absorbed or evolved

Here is the formula

ΔU =ΔQ – ΔW

WORK

• In thermodynamics, the total energy exchange between the system and surroundings is called work done. It is judged mainly by external factors like temperature, pressure, volume, external force, etc. All heat, work, and internal energy are interrelated
• It may be positive or negative as it depends upon the path of the initial and final state.

For example, the cylindrical vessel is filled with gas, and the piston covers the top. If the piston is moving upward, work done is positive. If the piston moves inward, it is negative.

HEAT

• The energy present in the form of heat is called heat energy. In a hot system, more heat energy is usually present in a cold system, and less heat energy is present.
• Compared to humans, polar bears and icebergs have more heat energy.
• The particles like atoms and molecules present in the objects collide with each other and produce the kinetic energy of the particles. It is the one that helps to understand the concepts in better ways. All heat work and internal energy are interrelated.

Heat depends on some of the factors such as

1. speed of the particle
2. size of the particle
3. number of the particles

Temperature is independent of all the factors mentioned above.

TRANSMISSION OF HEAT

There are three ways involved in the transmission of heat

1. Conduction
2. Convection
3. Radiation

CONDUCTION

• Conduction takes place and is solid. It is because liquid and glass are considered poor conductors. But mercury is an exception.
• If the solid body is heated, the atoms and molecules present in the solid body begin to move, letting it take the place of collision. They will gain kinetic energy, and the molecules present in the solid mass begin to vibrate. 
• Due to the transfer of heat from one particle to another, the particles begin to vibrate each other. This process is called conduction.
• If the particles present in the body are closely attached, more force is required to transfer energy from one particle to another. This type of body is called a good conductor.

CONVECTION

• Here in this process, heat flows in liquid and gasses.
• For example, if you put the vessel of broth in the oven and heat it, the lower part of the broth closer to the stove warms up faster than the upper part of the broth. After sometimes the lower part of the broth comes up and the upper part of the broth goes down, you can see the circulation of heat running between the broth in the vessels, but the heat conveyor can’t be seen with naked eyes. The circulation of the upside and lower sides of the broth where the whole vessels get heated up.

RADIATION HEAT TRANSFER

Here in this process, we obtained heat energy from the sun. There is no medium required to transfer heat energy in this process. It can travel in space just like radio waves and microwaves, they can transfer in electromagnetic waves.

CONDUCTION, CONVECTION and RADIATION

By direct contact, heat transfer takes place between two objects. In the case of conduction, heat transfer takes place between fluids. In the case of convection, heat transfer takes place by electromagnetic waves in the heating case of radiation.

Heat transfer occurs when the objects have two different temperatures and two different densities. If the object temperature is greater than 0 K, heat transfer takes place.

In the conduction process, heat transfer is slow. In the convection process, heat transfer is faster In the radiation process, heat transfer is the fastest.

Conduction process heat transfer takes place in solid objects and by electromagnetic waves.

 Convection process heat transfer takes place in intermediate objects, like convection between air and water.

It does not obey the law of reflection. It does obey the law of reflection and refraction.

CONCLUSION

All heat, work and internal energy are interrelated. In this topic, we have learned about work, internal energy, and heat. We have seen different types of transmission of heat such as conduction, convection and radiation. We have also seen some examples related to internal energy, work, and heat.