What is the molar mass of a gas that has a density of 2.62 g/L at 2.00 atm and 25.0°C?

Question

Quizplus · Accepted Answer

To find the molar mass, we need to use the ideal gas law:

PV = nRT

where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature.

We can rearrange this equation to solve for n/V, which is the density:

n/V = P/RT

Now we can substitute the given values:

density = 2.62 g/L 
P = 2.00 atm 
R = 0.0821 L atm /(mol K) 
T = 25°C + 273 = 298 K

n/V = (2.00 atm) / (0.0821 L atm /(mol K) * 298 K) 
n/V = 1.004 mol/L

We know that the molar mass is equal to the mass per mole of a substance, so we can find it by multiplying the density by the molar volume:

molar mass = (density) * (molar volume) 
molar mass = (2.62 g/L) / (1.004 mol/L) 
molar mass = 2.61 g/mol

The closest answer choice to this value is A) 32.0 g/mol.

What Is the Molar Mass of a Gas That Has