The vastness of entropy

[In?this?post,?I?have?emptied my?current?knowledge?and?understanding?of?entropy. This?will?be?available?on?the?internet?for?a?long?time?and?will?teach?youngsters the?meaning?of?entropy?as?they?grow?and?begin?to?wonder,?"What?is?entropy" as I did]

What is entropy?

I'm not sure Rudolf Clausius knew he discovered a powerful demon who rules the universe when he invented entropy.

Entropy is the arrow of time. Entropy is increasing with time.

Entropy was born with the creation of the universe and dies with its demise. Without entropy, the universe cannot exist. ?

Just like in finance, every transaction comes with a tax. Entropy is a tax at source for the conversion of heat to work. The universe is run by the entropy paid by heat.

In many cases, you would find a close relation between thermodynamics and human behavior. A person in a situation where he feels completely relaxed, totally composed, and is sure of himself or in control of himself always has more capability to work in any form. He is more motivated to do work. Molecules behave exactly like this. A relaxed molecule relatively can focus more on work than when there is too much chaos that distracts the molecule to do work. It loses focus on work and engages itself to cope up with chaos/disorder. The same applies to entropy. Entropy is always increasing in the universe in everything. Because everything in nature wants to go to a stable state of equilibrium from high energy to a low energy by dissipating its energy by creating disorder. This disorder is entropy.

Definitions of entropy

-Entropy is a disorder of molecules

-Entropy is a loss of energy when heat converts to work

-Entropy is energy loss in Joule/mole-K expressed as ?S = Q/T

-Entropy is the spread of energy

-Entropy measures how far a system is from equilibrium

-Entropy at equilibrium ?H = T?S, no enthalpy available to do work at equilibrium.?

-Entropy at equilibrium is zero. No entropy at equilibrium expressed as ?S = Q rev/T Joule/mole-K

- Entropy is an arrow of time: Entropy is an arrow of time. With time entropy is increasing and free energy is reducing. Time is not reversible. Time is only moving forward. The time arrow points toward the future. If the entropy reduces arrow of time will point toward the past.

How and when entropy changes?

-Entropy changes when the heat does work by compression/expansion.

-Entropy does not change if heat flows between two points like a heat exchanger unless there is a phase change

-Entropy changes when a process is irreversible

-Entropy changes with temperature

At constant Q the entropy S can only increase if there is a reduction in temperature. This reduction of energy provides kinetic energy to the molecules to increase motions and hence the temperature.

With changing Q entropy increases with rise in temperature

-Entropy changes with an increase in the concentration of molecules

-Entropy reduces with an increase in pressure. Increased pressure brings the molecules closer and reduces disorder

-Entropy increases with the increasing number of molecules or more spread of molecules. More spread of molecules means more disorder.

-Entropy increases with the size of a molecule

?-Entropy increases with an increase in volume

-Entropy changes with specific heat. For a change in temperature T k the entropy changes by Q/T, if Q is the heat. The same Q/T is the specific heat of the substance if the mass is constant. The higher the specific heat capacity, the smaller the temperature change for the same amount of heat applied to the same mass of substance, therefore smaller the entropy increase. Entropy and specific heat are two sides of the same coin. Both have the same units, J/mole-k. The main distinction between heat capacity and entropy is that heat capacity is dependent on the material or object, such as measuring the change in temperature when the material absorbs energy, whereas entropy is independent of any object.

Entropy changes with latent heat. The more latent heat the more breakdown of molecular clusters held by intermolecular forces. The more disorder. Example: The entropy increase when saturated water converts to saturated steam.

-Entropy of a pure substance at a given temperature is the sum of all the entropy it would acquire on warming from absolute zero (where S=0) to the particular temperature.

- Entropy does not change for ideal gases because there is no work. ?

-Entropy change does not alter the temperature. Entropy gets generated only when the heat does PV work. Every time a gas molecule does PV work its actual volume change is not V it is

( V - b). b is the van der Walls constant for real gases. ' b ' is the volume of the molecule.

?Therefore, every time gas molecules perform work it is less by van der Walls constant ' b '.

?Every time a gas molecule displaces another the displacement is less by the " van der Walls constant. ". This is what entropy loss fundamentally means. Entropy is the loss of work. It has nothing to do with temperature change. This explains why entropy increases with molecular weight and size. Entropy loss in an ideal gas is zero because the " van der Walls constant " does not figure in an ideal gas Therefore, strictly speaking, the 1st law of thermodynamics H = U + PV applies to only ideal gases. It does not account for entropy. If you just let the heat flow between two points there is no work so no entropy loss.

-Entropy increases in the isobaric process

-Entropy does not change in the iso-volumetric process

-Entropy does not increase in isothermal systems with the system and surrounds being at the same temperature.

-Entropy can increase in adiabatic systems if it is an irreversible system. An internally reversible adiabatic system is isentropic

-Entropy increases in isolated systems.

An isolated system is a closed system that can neither transfer nor receive heat, work, or mass. In other words, the path for energy transfer into or out of a closed system is closed. An isolated system's only source of energy is its own internal energy. Because its temperature is constant, so is its total kinetic energy. However, molecular collisions do occur at the given temperature based on their kinetic energy. When one molecule collides with another, one slows down while the other accelerates, but the total momentum remains constant because momentum is conserved. Consider what happens when the velocity of some molecules increases while the total energy remains constant. This increases the molecule's spread continuously within a confined space. Imagine 10^23 molecules/mole repeating this every moment. This is big chaos happening in the system. This lowers the density of molecules per unit area, resulting in more microstates and increased entropy.

-Entropy increases with more microstates

Entropy and Probability

Microstates: Explanation

A microstate is a term used to describe the number of different possible arrangements of molecular position and kinetic energy at a particular thermodynamic state. A process that gives an increase in the number of microstates, therefore, increases the entropy.

The interpretation of entropy is the measure of uncertainty, which remains about a system after its observable macroscopic properties, such as temperature, pressure, and volume, have been taken into account. For a given set of macroscopic variables, the entropy measures the degree to which the probability of the system is spread out over different possible microstates.

In contrast to the macrostate, which characterizes plainly observable average quantities (temperature, for example), a microstate specifies all molecular details about the system, including the position and velocity of every molecule. With more available microstates, the entropy of a system increases. This is the basis of an alternative (and more fundamental) definition of entropy:

S = k ln w

In this, k is the Boltzmann constant (the gas constant per molecule, 1.38 x 10^-23 J/K ) and w is the number of microstates that correspond to a given macrostate of the system. The more such microstates, the greater the probability of the system being in the corresponding macrostate. For any physically realizable macrostate, the quantity w is an unimaginably large number.

Entropy and Microstates

As explained, a microstate (W) is a specific configuration of the locations and energies of the atoms or molecules that comprise a system like the following:

S=k ln W

As for other state functions, the change in entropy for a process is the difference between its final (Sf) and initial (Si) values:

ΔS=Sf?Si= [ k lnWf?k lnWi ] = k ln Wf /Wi

For processes involving an increase in the number of microstates, Wf > Wi, the entropy of the system increases, ΔS > 0. Conversely, processes that reduce the number of microstates, Wf < Wi, yield a decrease in system entropy, ΔS < 0.

Absolute entropy

As you are aware, energy values are all relative and must be defined on a completely arbitrary scale; because there is no such thing as absolute energy of a substance, we can arbitrarily define the enthalpy or internal energy of an element in its most stable form at 298K and 1 atm pressure as zero. Entropy, on the other hand, is a measure of the "dilution" of thermal energy, so the less thermal energy available to spread through a system (that is, the lower the temperature), the smaller its entropy. In other words, as a substance's absolute temperature approaches zero, so does its entropy. This principle serves as the foundation for the third law of thermodynamics which says that the entropy of a perfectly solid at 0 K is zero.

If there is no entropy, the universe will come to an end

What does no entropy mean?

No chemical reactions: In the absence of entropy, the universe will have extremely high free energy. Both reactants and products will have the same free energy. There would be no chemical reactions or chemical processes.

All processes will be extremely slow: The irreversibility of a process causes entropy. Without entropy, the universe would be a reversible slow process in equilibrium with its surroundings.

No heat transfer from high to low temperature: Heat transfer takes place in the direction of entropy increase from high to low temperature.

Heat will no longer be a path function: Heat is always in transit because it is being chased by entropy.

No phase change: Entropy is a disorder. Because entropy always increases, there is a phase change. When water is boiled, it converts to steam because it can no longer accommodate entropy. To share its entropy, water moves to a higher energy state known as vapor.

That means there will be no steam and only low-energy hot water to do any mechanical work. So, no mechanical work.

No volume expansion: Without entropy, there would be no new microstate. The temperature has no effect on volume. Nothing will be compressible.

There is no thermodynamic work and everything is incompressible: Entropy is created when heat is converted to work. There would be no thermodynamic work if there was no entropy.

No equilibrium: There will be no equilibrium: all processes will be unidirectional. The human body is in balance with its surroundings. Entropy regulates our body temperature by making us sweat and cooling us down. In the absence of a place to dump the entropy, humans will experience significant increases in body fluctuations. temperature.