Question

3.45 g of an unknown gas at 55°C and 1.10 atm is stored in a 2.55-L flask. What is the density of the gas?

Answer 1

1.35 g/L

Explanation:

1) Use PV = nRT to determine moles of gas present in gas:

(1.10 atm) (2.55 L) = (n) (0.08206) (328 K)

n = 0.104 mol

2) Get molar mass of gas using calculated moles:

0.104 mol x M g/mol = 3.45g

M = 3.45 g / 0.104 mol = 33.17 g/mol

Density = Molar Mass x P / RT

= 33.17 g/mol x 1.10 atm / 0.0821 L mol / atm .K x 328 K

= 1.35 g /L