Answer
$\Delta S=22\frac{J}{K}$
Work Step by Step
We know that:
$\Delta S=nR\ln(\frac{V_f}{V_i})+nC_V\ln(\frac{T_f}{T_i})$
We plug in the known values to obtain:
$\Delta S=1.5\times \frac{5}{2}\times 8.314\times \ln(2)=21.6\frac{J}{K}\approx22\frac{J}{K}$
