Question

8.2L of an ideal gas weight 9.0 gm at 300 K and one atmospheric pressure . the molecular mass of gas is

Answer 1

note if the value of r is taken as 0.08314 then different answer will come so answer the question on the basis of the value provided in exam .

Answer 2

Answer: The molecular mass of gas is 27 g/mol.

Explanation:

To calculate the number of moles, we use the equation given by ideal gas equation:

$PV=nRT$

Or,

$PV=\frac{m}{M}RT$

where,

P = pressure of the gas = 1 atm

V = Volume of gas = 8.2 L

m = mass of gas = 9.0 g

M = molecular mass of gas = ?

R = Gas constant = $0.0820\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the gas = 300 K

Putting values in above equation, we get:

$1atm\times 8.2=\frac{9g}{M}\times 0.0820\text{ L atm }mol^{-1}K^{-1}\times 300K\\\\M=27g/mol$

Hence, the molecular mass of gas will be 27 g/mol.