Question

A sample of an unknown compound is vaporized at 170 C. The gas produced has a volume of 1980 ml at a pressure of 1 atm, and it weighs 5.17 gr. Assuming the gas behaves as an ideal gas under these conditions, calculate the molar mass of the compound. Round your answer to 3 significant digits.

Answer 1

The molar mass is 95.7 g/mol

Step-by-step explanation:

As the vapor formed is showing ideal gas behavior, it will obey ideal gas law.

PV = nRT

Where

P = Pressure = 1 atm

V = volume = 1980 mL = 1.98 L

n = moles of gas

R = gas constant = 0.0821 L atm /mol K

T = Temperature = 170 °C = 170+273 = 443 K

Putting values

1 X 1.98 = n X 0.0821 X 443

n = moles = 0.054 mol

the relation between moles and molar mass and mass is:

`moles=(mass)/(molarmass)`

Therefore

`molarmass=(mass)/(moles)=(5.17)/(0.054)=  95.7 g/mol`