# Isobaric Process - Entropy in Terms of Pressure and Volume

Written by Jerry Ratzlaff on . Posted in Thermodynamics

Isobaric process is a thermodynamic process where the pressure is kept constant, $$\Delta p = 0$$.

## Isobaric process - entropy in terms of pressure and volume Formulas

 $$\large{ S = \Delta S \; \left( - n\; R \right) \; \left[ ln \left( \frac{p_f}{p_i} \right) \right] }$$ $$\large{ S = \Delta S \; \left( n\; R \right) \; \left[ ln \left( \frac{V_f}{V_i} \right) \right] }$$

### Where:

$$\large{ S }$$ = entropy

$$\large{ \Delta S }$$ = change in entropy

$$\large{ R }$$ = molar gas constant

$$\large{ ln }$$ = natural logarithm

$$\large{ n }$$ = number of moles

$$\large{ p_f }$$ = final pressure

$$\large{ V_f }$$ = final volume

$$\large{ p_i }$$ = final pressure

$$\large{ V_i }$$ = initial volume