Saturated water vapor at 400°F is heated at constant pressure until its volume has doubled. The gas constant, the critical pressure, and the critical temperature of ethane are R = 0.5956 psia·ft3/lbm·R, Tcr= 1164.8 R, and Pcr= 3200 psia. Use data from the steam tables.

Ahe-xe mixture containing a 0.75 mole fraction of helium is used for cooling electronics in an avionics application. at a temperature of 300 k and atmospheric pressure, calculate the mass fraction of helium and the mass density, molar concentration and molecular weight of the mixture. if the cooling capacity is 10 l, what is the mass of the coolant?