How many mol of N2 gas will occupy a 4.01-L container at STP?

Answer 1

An alternative solution to Brian's answer is knowing that at STP, 1 mol of a gas will occupy a volume of 22.4 L. In this way, you can setup a proportion.

1 mol = 22.4 L

x mol = 4.01 L

Solve for x = 4.01 L x (1 mol / 22.4 L) = 0.179 mol (rounded to 3 significant figures)

Answer 2

STP means Standard Temperature & Pressure which means Temperature (T) = 298 K and

Pressure (P) = 1 atm.

Ideal Gas Law: PV = nRT (R = 0.08205 L*atm/mol*K)

Rearrange equation in order to find mols.

n = PV/RT

Now Plug in all the values to calculate number of mols (N2)

n = (1 atm)(4.01 L)/(0.08206 L*atm/mol*K)(273 K)

All the units (atm, L, K) cancel each other out except for mol unit.

Therefore,

n = 0.18 mols of N2 gas