Entropy as State Function

Entropy is a numerical term in thermodynamics that illustrates that many physical processes can only go in one way in time. For example, you can pour cream into coffee and mix it, but you can’t “unmix” it, just as you can’t “unburn” a piece of wood. The term ‘entropy’ means a lack of order or predictability, as well as a steady descent towards chaos. The dispersion of energy or matter, or the amount and diversity of microscopic motion, is a more physical explanation of thermodynamic entropy .

Entropy :

The quantity of energy that is unavailable to conduct work is measured by an object’s entropy. Entropy is also a metric for the amount of alternative configurations for atoms in a system. Entropy is a measure of uncertainty or unpredictability in this sense. Entropy cannot continue to grow endlessly. A body of matter and radiation will eventually reach an unchanging state with no discernible flows, which is known as thermodynamic equilibrium. For such a body, thermodynamic entropy has a fixed value and is at its maximum value. When bodies of matter or radiation, which are each in their own state of internal thermodynamic equilibrium, are brought together in such a way that they interact intimately and reach a new joint equilibrium, their total entropy rises. A glass of warm water with an ice cube in it, for example, will have a lower entropy than the same system after the ice has melted and left a glass of cool water. These are irreversible processes: A glass of cool water will not spontaneously form an ice cube in a glass of warm water. Some natural processes are almost reversible. The orbiting of the planets around the sun, for example, can be considered essentially reversible: It does not appear that a reversed movie of the planets orbiting the sun is impossible .

Entropy meaning :

Entropy is a measure of chaos that has an impact on many facets of our existence. In fact, it’s akin to a tax imposed by nature. If problem is not addressed, it will worsen over time. Energy dissipates, and systems disintegrate. We consider something to be more entropic if it is more chaotic .

Unit of entropy :

Entropy is measured in J/K units. In this equation, the temperature must be measured on the absolute, or Kelvin, scale. On this scale, zero is the lowest temperature that any substance may theoretically reach. Its having unit in C.G.S is Cal/Kmol.

Relation between Entropy and Heat :

If the number of particles in a particular process is limited (dN = 0), then:

On the other hand, we have energy conservation:

dU = δW + δQ

AS the work is: δW  =  – P dV , Hence we get the relation between heat and entropy:

δQ  = T dS

Flux of heat increases its entropy when it is inside the system. 

Properties of Entropy :

• It is a result of thermodynamics.
• It’s a state function, after all. The condition of the system, rather than the path taken, determines it.
• It is represented by S, however it is represented as S° in the ordinary state.
• The SI unit for it is J/Kmol.
• The CGS unit is Cal/Kmol.
• Entropy is a scalable property, meaning it grows in proportion to the size or scope of a system.

Entropy Formula:

Entropy is a thermodynamic function that is used to quantify a system’s uncertainty or disorder. Furthermore, the entropy of a solid (closely packed particles) is higher than that of a gas (particles are free to move). Furthermore, scientists have found that the entropy of a spontaneous process must rise. It also takes into account the system’s entropy as well as the entropy of the environment .

Furthermore, there are numerous equations for calculating entropy:

1. If the process is taking place at a constant temperature, entropy will be constant.

∆Ssystem = qrevT

Derivation of Entropy Formula

ΔS = is the change in entropy

qrev = refers to the reverse of heat

T = refers to the temperature in Kelvin

2) Furthermore, assuming the process reaction is known, we can use a table of conventional entropy values to find ∆Srxn.

 ∆Srxn  = Σ ∆Sproducts– Σ ∆Sreactants

Derivation

 ∆Srxn –  refers to the standard entropy values

Σ∆Sproducts  = refers to the sum of the  ∆Sproducts

Σ∆Sreactants  – refers to the sum of the  ∆Sreactants

3) Is it possible to find ∆S using the Gibbs free energy (∆G) and the enthalpy (∆H):

ΔG = ΔH – TΔS

Conclusion:

If entropy has been steadily increasing, there must have been a point in the past when it was zero, because negative entropy makes no sense. If this is the case, it supports the Big Bang theory because the entropy value of zero can only be reached when the entire universe is a singularity.