The density of an ideal gas is 1.25 × 10^–3 g cm^–3 at STP. Calculate the molecular weight of the gas.

We know ideal gas equation

PV=nRT

Where V= volume of gas

R=gas constant

T=temperature

n=number of moles of gas

P=pressure of gas

STP means standard temperature-273.15K and pressure 101.325 kPa.

Given:

T=273.15K

P=101.325Pa

Density of ideal gas 1.25 × 10^–3 g cm^–3

1gcm^-3=10³kgm³

kgm³

Number of moles n ==

Density

From ideal gas equation, we can write

Molecular weight of gas is 2.3810^-2gmol^-1