Calculate the molar weight of Freon-II, if 8.29 liters of its vapor at 200 °C and 700 mm Hg has a mass of 30.5 g?
this problem can be solved using the ideal gas equation.
`PV = nRT`
P = pressure in atm = 700/760 = 0.9211atm
V = volume = 8.29L
R = gas constant, 0.08206 atm-L/mol-K
T = temperature in Kelvin = 200 + 273 = 473
n = numbers of moles = Mass/molar mass
mass of the compound = 30.5
we can rewrite the equation above as
`PV = (Mass)/(Molar mass) * RT`
by arranging this we can solve for Molar mass
`Molar mass = Mass (RT)/(PV)`
`Molar mass = 30.5 * (0.08206*473)/(0.9211*8.29)`
Molar mass = 155 g/mole
check Approved by eNotes Editorial