PV = nRT —> n = PV/RT
P = 2.90 atm
V = 4.80 L
R = 0.08206 L atm / mol K
T = 62.0 + 273 = 335 K (make sure you convert from celsius to kelvin)
n = (2.90 • 4.80) / (0.08206 • 335) = 0.506 moles of gas
Density = mass / volume. So you'd write it out as D = 56g / 60.9cm^3, giving you 0.9195 g/cm^3.
