If the density of an unknown gas #Z# 4.50 g/L at STP, what is the molar mass of gas #Z#?

1 Answer
May 17, 2016

Answer:

#P.MM= d.R.T#

Explanation:

Use the ideal gas equation

#P.V=n.R.T#

#P.V= m/(MM).R.T#

#P.MM= m/V.R.T#

#P.MM= d.R.T#

#P" is the pressure of the gas (" atm")"#
#MM" is the molar mass ("g.mol^-1")"#
#d" is the density of the gas ("g.L^-1")"#
#R" is the universal gas constant ("0.0821*L.\atm.mol^-1.K^-1")" #

Solve for #MM#

#MM= (d.R.T)/P#

#MM=(4.50*g*L^-1* 0.0821*L*atm*mol^-1*K^-1*273*K)/(1.00*\atm)#

#MM ~= 101" "g.mol^-1#