Question

Calculate the weight of the following gas which occupy a volume of 3.36 dm³ at STP:

nitrogen

Answer 1

Concept used:

According to the mole concept, one mole is the amount of the gas which has a volume of 22.4 l at STP.

Also, 1 mole= Gram molecular weight

Therefore, Gram molecular weight= 22.4 l of the substance at STP

Or Gram molecular weight= 22.4 dm³ of the substance at STP (1 litre= 1 dm³)

Step-1: Calculation of the gram molecular weight of Nitrogen (N₂)

Gram atomic weight of Nitrogen (N)= 14 g mol^-1

Gram molecular weight of Nitrogen gas (N₂)= 2 (14)= 28 g mol^-1

Step-2: Calculation of weight in a volume of 3.36 dm³ at STP

For Nitrogen gas, the Molecular weight is 28 g.

22.4 dm³ of Nitrogen gas (N₂) weighs= 28 g

1 dm³ of Nitrogen gas (N₂) weighs= $\frac{28}{22.4}$ g

3.36 dm³ of Nitrogen gas (N₂) weighs= $\frac{28}{22.4}\times 3.36=\frac{94.08}{22.4}=4.2$ g

Therefore, the weight of the Nitrogen gas which occupy a volume of 3.36 dm³ at STP is 4.2 g.