Question

A 1.85−L vessel contains 4.60 g of a gas at 1.00 atm and 27.0°C. (a) Calculate the density of the gas in g/L. (b) What is the molar mass of the gas?

Answer 1

a) PV = nRT

where, P = pressure = 1.00 atm

V = volume = 1.85 L

n = number of moles

R = Gas constant

T = temperature = 27.0 + 273 = 300 K

1.00 * 1.85 = n * 0.0821 * 300

1.85 = n * 24.6

n = 1.85 / 24.6 = 0.0752 mole

number of moles = mass / molar mass

0.0752 mole = 4.60 g / molar mass

molar mass = 4.60 g / 0.0752 mol = 61.2 g/mol

Therefore, molar mass of gas = 61.2 g/mol

b) P * molar mass = density * R * T

1.00 * 61.2 = density * 0.0821 * 300

61.2 = denisty * 24.6

denisty = 61.2 / 24.6 = 2.49 g/L