A mouse is placed in a sealed chamber with air at 761.0 torr. This chamber is equipped with enough solid KOH to absorb any CO2 and H2O produced by the mouse. The gas volume in this chamber is measured to be exactly 1.90 L, at the temperature is held constant at 294 K. After two hours the pressure inside the bottle falls to 721.3 torr. What mass of molecular oxygen has the mouse consumed? Enter units.