Answer
$\Delta S=14.4\frac{J}{K}$
Work Step by Step
For an isothemal process, we know that:
$T_i=T_f$
We also know that:
$\Delta S=S_f-S_i=nR\ln\frac{v_f}{v_i}+nC_v\ln \frac{T_f}{T_i}$
As $\ln \frac{T_f}{T_i}=0$;
$\Delta S=nR\ln\frac{v_f}{v_i}$
We plug in the known values to obtain:
$\Delta S=2.50(8.31)\ln(2.00)=14.4\frac{J}{K}$
