text: partial pressure and mass? in a mixture of   ne   and   h2   gases, the partial pressure of   ne   is   0.180 atm.   the total pressure is   0.410 atm.   the temperature is   28.0oc.   if the total volume of the gas mixture is   421 ml,   what is the mass of   h2   in grams? the partial pressure of h2 is just the total pressure minus the partial pressure of ne.  the ratio of the h2 part press and total press gives the mole fraction of h2.    now just calculate the number of moles in your 421 ml using the ideal gas equation  pv = nrt.  solve for n, multiply this by the mole fraction of h2 to get the moles of h2, then multiply this by the mole weight of h2.  i'll let you do the math.