Biomolecules, enzyme kinetics

Consider a piston-cylinder assembly shown in the figure below. The walls of the cylinder are insulated. The cylinder contains 1 mole of an ideal gas at 300 K and the piston is held initially at the position z1 using a stopper. After the stopper is removed, the piston suddenly rises against atmospheric pressure (1.013×105 Pa) to the new position z2 where it is held by another stopper. The heat capacity (Cv) of the gas is 12.5 J mol-1 K-1. The cross-sectional area of the cylinder is 10-3 m2. Assume the piston is weightless and frictionless. If 𝑧ଶ− 𝑧ଵ = 1 m, the final temperature of the gas (rounded off to nearest integer) is ___________K.