Question

How do you calculate molecular weight of a gas?

Answer 1

`MM=(mRT)/(PV)`

Explanation:

To find the molecular mass of a gas, we can assume it behaves ideally and use the ideal gas law:

`PV=nRT`

We can modify this law in terms of the molar mass (`MM`).

We know that the number of mole is equal to the mass (`m`) divided by th molecular mass (`MM`) of the gas:

`n=m/(MM)`

If we plug the expression of number of mole in the expression of the ideal gas law we get:

`PV=m/(MM)RT`

therefore, the molecular mass expression can be written as:

`MM=(mRT)/(PV)`

Thus, to find the molecular mass of a gas, we can measure its pressure, volume, mass and temperature.