7. Calculate the density of hydrogen sulfide, H2S, at 56 ºC and 967 mmHg. (Express density in g/L)

Answer 1

If you modify the formula for ideal gas (PV = nRT) a little, you'll get an expression for the density of gas:
ρ = P*MM / RT
where
ρ = density (g/L)
P = pressure (atm)
MM = molar mass (g/mol)
R = universal gas constant = 0.0821 L-atm/mol-K
T = absolute temperature (K)

Note that the molar mass of H2S is
2*1 + 1*32 = 34 g/mol
This is a direct substitution, but don't forget to convert the units:
ρ = ((967 / 760) * 34) / (0.0821 * (56 + 273))
Now you can solve for ρ.

hope this helps~ `u`