ideal gas law question!!?

How many moles are present in a 500 mL sample of hydrogen gas, which is at 1.35 atm and 25 C? What about with chlorine gas? What is the difference if it is with H2 or Cl2??? I am using ideal gas law and i get .0276 mol, but wouldn't it be the same for both??? what variable do i change when solving for a different gas???