Answer
$1.20\times10^{3}\,mmHg$
Work Step by Step
Ideal gas law is written as
$pV=nRT$
As $n=\frac{m}{M}$,
$pV=\frac{m}{M}RT$
Or alternatively, we can state it as
$pM=dRT$ where p is the pressure, M is the molar mass, d is the density, R is the universal gas constant and T the temperature.
Given/Known: d= 2.85 g/L, T= 298 K,
$R=0.082057\,L\,atmK^{-1}mol^{-1}$ and M= 44.0 g/mol.
Equation to find p:
$p=\frac{dRT}{M}$
Result: $p=\frac{2.85\,g/L\times0.082057\,L\,atmK^{-1}mol^{-1}\times298\,K}{44.0\,g/mol}=1.58\,atm$
$1.58\, atm=1.58\,atm\times\frac{760\,mmHg}{1\,atm}=1.20\times10^{3}\,mmHg$
