Work Done in all Expansions in Thermodynamics

Chemists are interested in how much work it takes to change the volume of a gas when it is under pressure from outside. When the gas gets bigger, it does more work. For example, in thermodynamics, work means the energy it takes to move something against a force. It’s called “work,” and it’s one of the main ways energy comes into or goes out of a system. Joules are the units of work. Consider a gas in a cylinder with a cross-sectional area, a. A weightless and frictionless piston is inside the cylinder.

Work done in all expansions in thermodynamics 

Chemists are very interested in the work that is involved in the change in volume of a gas when compared to the change in external pressure. The work performed as a result of the expansion of the gas is referred to as the work of expansion. Work, on the other hand, has a very specific meaning in thermodynamics: it is the amount of energy required to move an object against a force. Work, denoted by the symbol w, is one of the most fundamental ways in which energy enters or leaves a system, and it is measured in Joules. Consider a gas that is contained in a cylinder with a cross-sectional area of a certain size and that is a. fitted with a piston that is both weightless and frictionless.

when the pressure on the piston is equal to P, the piston comes to a state of equilibrium. The force acting on the piston is equal to P x a, which is the product of the pressure multiplied by the area. When the piston is raised by a certain distance, h, allow the gas in the cylinder to expand. In this case, because h has caused the point of application of the force to be displaced, the amount of work done against the force is equal to Pxaxh However, the change in volume, V, is equal to the product of a and h. As a result, the task of expansion will be;

w = – P x V……….. (1)

The presence of a negative sign in equation (1) indicates that the gas is exerting pressure on its surroundings. Vf and Vi are the final and initial volumes of the gas, respectively, in equation (1), where V (= Vf–Vi) denotes the change in volume (= Vf–Vi) of the gas. The expansion of a gas has a value greater than zero, and the product of the two quantities is negative.

When it comes to compression (work done on the system), V is equal to zero, and P x V is a positive quality. Assuming that the gas is ideal, PV can be replaced by RT for one mole, and the work of expansion is the same as RT. The units in which work will be expressed will be determined by the units of P and V, respectively.

An Ideal Gas Expansion Isothermally

Expansion due to isothermal heat

Ideal gases have no intermolecular attraction because molecules in an ideal gas travel so rapidly that they don’t interact with one other. Real gas, on the other hand, does not have any intermolecular attraction. There is no such thing as an ideal gas in nature. Gases, on the other hand, perform best at high temperatures and low pressures. In an ideal gas, all of the internal energy is in the form of kinetic energy, and any change in the internal energy causes a change in the temperature.

An ideal gas has been defined, therefore let’s look at the definition of an isothermal expansion and its related term, isothermal process. An isothermal process is one in which the temperature of the system does not change at all. To put it another way, in an isothermal situation, T = 0.

When a gas expands in a vacuum (pex=0), it is free to expand. Whether the process is reversible or irreversible, no work is done during the free expansion of a perfect gas.

It is known that the change in internal energy of a system is provided as:

q + w— (1)

Where ∆U represents the change in internal energy, q is the heat given by the system and w is the work done on the system.

It is possible to write the above equation in a variety of ways, depending on the procedure.

w = pexV is the work done in a vacuum. As a result, we can write equation 1 as follows:

To get the answer, you need to know the following:

V = 0 if the process is carried out at a constant volume. Thus,

q = u -lrb-

The prefix qv denotes that the heat is delivered in a uniform volume.

Isothermal expansion (T = 0) of an ideal gas in vacuum results in no work being done since pex=0. Because Joule experimentally found that q = 0, U = 0, q = 0.

Equation 1 can be written as follows for both reversible and irreversible isothermal changes:

q = -w = pex isothermal reversible change (Vf-Vi)

q = -w = nRTln (Vf/Vi) = 2.303 nRT log (Vf/Vi) Isothermal reversible change

Q=0, U=wad Adiabatic change

Adibatic  process

It is well known that heat, temperature, and the surrounding environment are all components that contribute to heat transfer between systems. When heat is transported, something happens. An adiabatic process is one in which no heat is transferred. Let’s take a closer look at the adiabatic process with examples in this post.

The adiabatic equation is as follows:

Constant PV is PV

Where,

P stands for the system’s pressure, which is measured in pounds per square inch.

The system’s volume is V.

The adiabatic index () is the heat capacity to pressure ratio at constant temperature. Constant volume, Cp, is the heat capacity Cv

Adiabatic Process that can be reversed

The Isentropic Process is another name for the reversible adiabatic process. In a reversible thermodynamic process, there is no transfer of heat or matter; instead, the system is adiabatic and the work exchanges are frictionless. Engineers can utilize such an idealized process as a model for and a reference point for real-world processes.

An example of an adiabatic process

Heat and pressure are created as a result of gas compression. Air may be released from pneumatic tires in the most straightforward way.

nozzles, compressors, and turbines are all examples of Adiabatic Efficiency. The adiabatic process has several useful uses.

A good example of this is a pendulum swinging in a vertical plane.

Another type of adiabatic system is a quantum harmonic oscillator.

No heat is lost or gained when we fill the icebox with water.

Conclusion

From the following article we can conclude that The work involved in changing a gas’s volume against an external pressure excites chemists. The work done by the gas expansion is the job of expansion. In thermodynamics, work is the energy required to move an item against a force. Work, w, is a fundamental method energy enters or exits a system. Consider a gas in a cylinder with a weightless and frictionless piston.