Question

What is the molar mass of a gas if it has a density of 2.40g/L at 851.2mmHg and 2°C

Answer 1

Answer: The molar mass of gas is 48.4 g/mol

Step-by-step explanation:

To calculate the relation of density and molar mass of a compound, we use the ideal gas equation:

`PV=nRT`

P = pressure = 851.2 mm Hg = 1.12 atm ( 760 mm Hg = 1atm)

V = Volume

n = number of moles

R = gas constant = 0.0821 Latm/Kmol

T = temperature =
`2^0C=(2+273)K=275K`

Number of moles (n) can be written as:

`n=(m)/(M)`

where, m = given mass

M = molar mass

where,

`P=(mRT)/(MV)`

`P=(dRT)/(M)`

where d = density

The relation becomes:

`M=(dRT)/(P)`

Putting the values we get :

`M=(2.40g/L* 0.0821Latm/Kmol* 275K)/(1.12atm)`

`M=48.4g/mol`

Thus molar mass of gas is 48.4 g/mol