We are given here that the volume ( V ) = 1.50 Liters, the initial moles ( held at 25 °C ) = 3.00 mol, and the final moles ( n ) = 3.00 - 0.5 = 2.5 mol. The final mol is calculated given that 0.50 mol of gas are released from the prior 3.00 moles of gas.
Volume ( V ) = 1.50 L,
Initial moles ( n ) = 3.00 mol,
Final Volume ( n ) = 3.00 - 0.5 = 2.5 mol
Applying the combined gas law, we can calculate the final volume ( V ).
PV / nT = PV / nT - we know that the pressure and temperature are constant, and therefore we can apply the following formula,
V / n = V / n - isolate V,
V = V n / n = 1.50 L 2.5 mol / 3.00 mol = ( 1.5 2.5 / 3 ) L = 1.25 L