Isobaric process
It is a process which occurs when the pressure of the system is constant(🛆P =0). The process in which volume and temperature changes without any change in Pressure is called as Isobaric process. Charles law describes the isobaric process well. According to Charles law at constant pressure, temperature of the system is directly proportional to volume. When we boil water at constant atmospheric pressure, the process is isobaric in nature. During isobaric process, none of the quantities Q, ΔU, W is zero.
Mathematical Expression for isobaric Process
let us consider a gas undergoing an isobaric process from initial state to final state.
From work equation we can write
W= PdV
If Ti and Vi and Tf and Vf are the temperature and Volume at initial and final state of the system, then we can write
W = PdV
W= P (Vf - Vi)---(1)
PV = nRT ---(2)
from (1) and (2)
W = nR (Tf - Ti) -----(A)
As the temperature is changing , thus internal energy will change given by,
ΔU = nCvΔT
ΔU = n Cv (Tf - Ti)-----(B)
From First law of thermodynamics,
Q = ΔU +W -----(C)
From A , B ,C
Q = n Cv (Tf - Ti) + nR (Tf - Ti)
Q = n Cv + nR (Tf - Ti)
Q = n (Cv + R) (Tf - Ti)
We know that ,
Cv + R) =Cp
Q = n Cp (Tf - Ti)
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