A volatile liquid produced 0.379 g of vapor in a 262.0-mL flask at 100.0°C and 0.960 atm. What is the molar mass of the liquid?

Question

Quizplus · Accepted Answer

First, we need to use the ideal gas law to find the number of moles of gas present:

n = PV/RT

where P = 0.960 atm, V = 0.262 L, T = 373.2 K (100.0°C + 273.2), and R = 0.08206 L atm/mol K.

n = (0.960 atm)(0.262 L)/(0.08206 L atm/mol K)(373.2 K) = 0.0112 mol

Next, we can use the mass and the number of moles to find the molar mass:

molar mass = mass/number of moles

molar mass = 0.379 g/0.0112 mol = 33.8 g/mol

This molar mass is close to choice C (46.1 g/mol), so it is the best choice.

A Volatile Liquid Produced 0