Question

A 0.215 g gas sample occupies a volume of 225 mL at 27°C and 740. mm Hg. What is the molar mass of this gas?

Answer 1

The molar mass of the gas is 126 g/mol.

Step-by-step explanation:

First calculate the moles of the gas using the gas law, PV=nRT, where n is the moles and R is the gas constant. Then divide the given mass by the number of moles to get molar mass.

Calculate Moles

Given/Known

mass:0.950 g

pressure:P=0.985 atm

volume:V=232mL×1L1000mL=0.232 L

gas constant:R=0.082057338 L atm K−1mol−1

temperature:T=95oC+273.15=368 K

Unknown

n

Equation

PV=nRT

Solution

Rearrange the equation to isolate n and solve.

n=PVRT

n=0.985atm×0.232L0.082057338L atmK−1mol−1×368K