Birth of Entropy
Entropy is the degree of randomness of a thermodynamic system.
In this article we will discuss how the concept of Entropy is originated in thermodynamics.
Let’s consider a reversible heat engine.
From the absolute thermodynamic scale of temperature, we know that.
Q1/Q2 = T1/T2
Q1/T1 – Q2/T2 = 0
Q1/T1 + (-Q2)/T2 = 0
ΣCYCLE (Q/T) = 0
In terms of cyclic integral we can write above equation as
∫CYCLE (∂QR/T) = 0
We all know that cyclic integral of only a property is zero.
It means ∂QR/T represents a property. Let’s say it dS.
dS = ∂QR/T
Integrating both sides
ΔS = ∫(∂QR/T)
S2 – S1 = ∫(∂QR/T)
We declare this point function ‘S’ as entropy.