Question

g A sample of unknown gas has a mass of 1.95 g and occupies 3.00 L at 1.25 atm and 20 C. What is the molar mass of the unknown gas

Answer 1

Molar mass = 12.51 g/mol

Step-by-step explanation:

V = 3L

P = 1.25 atm

T = 20 C = 20 + 273 = 293 K (Upon conversion to kelvin temperature)

n =?

m = 1.95g

Molar mass = ?

The variables are related by the follwing equation;

pV = nRT

where r = gas constant = 0.0821 L atm K−1

Solving for n, we have;

n = pV / RT

n = (1.25 * 3 ) / (0.0821 * 293)

n = 3.75 / 24.0553 = 0.1559 mol

The relationship between number of moles, n and molar mass is given as;

n = mass / molar mass

Molar mass = Mass / n = 1.95 / 0.1559

Molar mass = 12.51 g/mol