What is the density of nitrogen gas (N_2) at standard temperature and pressure (STP)?

• A. 2.01 g/L
• B. 1.25 g/L
• C. 0.89 g/L
• D. 0.44 g/L

Answer: (B)

Verified step by step guidance

1. Recall that the density (\(d\)) of a gas can be calculated using the formula \(d = \frac{m}{V}\), where \(m\) is the mass of the gas and \(V\) is its volume.
2. At standard temperature and pressure (STP), one mole of any ideal gas occupies 22.4 liters. This is a key fact to use for volume calculations.
3. Calculate the molar mass of nitrogen gas (\(N_2\)). Since nitrogen has an atomic mass of approximately 14.0 g/mol, the molar mass of \(N_2\) is \$2 \times 14.0 = 28.0$ g/mol.
4. Use the molar mass as the mass (\(m\)) of one mole of nitrogen gas and the molar volume at STP (22.4 L) as the volume (\(V\)) to find the density: \(d = \frac{28.0 \text{ g}}{22.4 \text{ L}}\).
5. Perform the division to find the density in g/L, which will give you the density of nitrogen gas at STP.