A 50.0 L cylinder of Ar has a pressure of 137 atm at 25 C. What mass of Ar is inside the cylinder?

A 50.0 L cylinder of Ar has a pressure of 137 atm at 25 °C. What mass of Ar is inside the cylinder? The lid is tightly sealed on a rigid flask containing 3.50 L H2 at 17 °C and 0.913 atm. If the flask is heated to 71 °C, what is the pressure in the flask?A 0.225-L flask contains CH4 at 27 °C and 318 mm Hg. What is the pressure of the CH4 if the volume is increased to 0.500 L and the temperature increased to 95 °C?