# How do you calculate molecular weight of a gas?

##### 1 Answer

Jun 3, 2016

#### Explanation:

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.