A gas sample containing 1.47 mol at 25C exerts a pressure of 401 torr. Some gas is added to the same container, and the temperature is increased to...

A gas sample containing 1.47 mol at 25°C exerts a pressure of 401 torr. Some gas is added to the same container, and the temperature is increased to 50.°C. If the pressure increases to 800. torr, how many moles of gas were added to the container? Assume a constant-volume container.