Question

a gas with a mass of 67.24 g occupies 20.00L and 730 mmHg.what is the molar mass of the gas in g/mol?

Answer 1

Answer:

The molar mass is 85.59 g/mol

Explanation:

Given:

m = mass = 67.24 g

V = Volume = 20 L

P = pressure = 730 mmHg

Question: What is the molar mass of the gas, PM = ?

The molecular weight of any susbtance is defined as the amount of mass over the number of moles.

$PM=\frac{m}{n}$

According to the ideal gas law:

$PV=nRT$

Clearing the number of moles from the first equation and replacing it in the second

$PV=\frac{mRT}{PM} \\PM=\frac{mRT}{PV}$

Here,

R = constant = 62.36367 mmHg L/mol K

T = 25°C = 298 K, we assume that the temperature is the standard.

Substituting values:

$PM=\frac{67.24*62.36367*298}{730*20} =85.59g/mol$