A vessel, divided into two parts by a partition, contains \(4 \mathrm{~mol}\) of nitrogen gas at \(75^{\circ} \mathrm{C}\) and \(30 \mathrm{bar}\) on one side and \(2.5 \mathrm{~mol}\) of argon gas at \(130^{\circ} \mathrm{C}\) and \(20 \mathrm{bar}\) on the other. If the partition is removed and the gases mix adiabatically and completely, what is the change in entropy? Assume nitrogen to be an ideal gas with \(C_{V}=5 R / 2\) and argon to be an ideal gas with \(C_{V}=3 R / 2\).