Chemistry density of gas in flask

Question

A 3.35 g sample of an unknown gas at 37 ∘C and 1.05 atm is stored in a 2.75 L flask.

What is the density of the gas?

density:

g/L

What is the molar mass of the gas?

molar mass:

g/mol

Answer 1

We are looking for density and molar mass of the unknown gas.

Density is defined as mass/volume

Molar mass is defined as grams/mole

For density, you are given both the mass (3.35 g) and the volume (2.75 L), so density = 3.35g/2.75 L

Density = 1.35 g/L

Using the ideal gas law we can determine the moles of unknown gas present and then the molar mass:

PV = nRT

P = 1.05 atm

V = 2.75 L

n = ?

R = 0.0821 Latm/Kmol

T = 37ºC + 273 = 310 K

Solving for n, we have....

n = PV/RT = (1.05)(2.75)/(0.0821)(310)

n = 0.113 moles

molar mass = 3.35 g/0.113 moles = 29.6 g/mole