Question

A student collects a sample of gas and finds that 1.01 g of the gas will fill a container with a volume of 0.225 L at STP. What is the molar mass of the gas?

Answer 1

`MM=101g/(mol)`

Explanation:

At STP, we know that the molar volume of a gas is `22.42L/(mol)`, therefore, now we can calculate the number of mole of the gas from its volume `V=0.225L` at STP.

`=>n=0.225cancel(L)xx(1mol)/(22.42cancel(L))=0.01 mol`

From the number of mole and the mass of the sample (`m=1.01g`) we can find the molar mass of the gas:

`n=m/(MM)=>MM=m/n=(1.01g)/(0.01mol)=101g/(mol)`