How do you calculate molecular weight of a gas?
To find the molecular mass of a gas, we can assume it behaves ideally and use the ideal gas law:
We can modify this law in terms of the molar mass (
We know that the number of mole is equal to the mass (
If we plug the expression of number of mole in the expression of the ideal gas law we get:
therefore, the molecular mass expression can be written as:
Thus, to find the molecular mass of a gas, we can measure its pressure, volume, mass and temperature.