Question

A sample of 4.25 L of nitrogen gas at STP has a mass of how many grams?

Show the rearranged ideal gas law solving for moles. Cancel units in work.

Answer 1

The rearranged ideal gas law solving for moles is: n = PV/RT

At STP, P = 1 atm and T = 273 K. The molar volume of a gas at STP is 22.4 L/mol.

So, n = (1 atm)(4.25 L)/(0.0821 L·atm/mol·K)(273 K) = 0.174 mol

The molar mass of nitrogen gas (N2) is 28.0 g/mol.

Therefore, the mass of 4.25 L of nitrogen gas at STP is:
mass = n × molar mass = 0.174 mol × 28.0 g/mol = 4.87 g

The mass of 4.25 L of nitrogen gas at STP is 4.87 grams.