Question

The entropy change when two moles of ideal monoatomic gas is heated from 200 to ${300}^{\circ }C$ reversibly and isochorically ?

• A. $\frac{3}{2}Rln\left[\frac{300}{200}\right]$
• B. $\frac{5}{2}Rln\left[\frac{573}{273}\right]$
• C. $3Rln\left[\frac{573}{473}\right]$
• D. $\frac{3}{2}Rln\left[\frac{573}{473}\right]$

Answer 1

The correct option is C $3Rln\left[\frac{573}{473}\right]$

$T_1=200+273=473K$

$T_2=300+273=573K$

$n=2$

Entropy change is given by,

$\Delta S=n{C}_{V}ln\left[\frac{T_2}{T_1}\right]$ for isochoric change.

$\Delta S=2\times \left[\frac{3}{2}R\right]ln\left[\frac{573}{473}\right]$

$\Delta S=3Rln\left[\frac{573}{473}\right]$