A container has two chambers of volumes V_1=2 litres and V_2=3 litres separated by a partition made of a thermal insulator. The chambers contain n_1=5 and n_2=4 moles of ideal gas at pressures p_1=1 \mathrm{~atm} and p_2=2 \mathrm{~atm}, respectively. When the partition is removed, the mixture attains an equilibrium pressure of