An 855 L tank is to be filled with nitrogen gas (N_2) at standard temperature and pressure (STP). What mass of nitrogen gas is required to fill the tank under these conditions?

• A. 1080 g
• B. 273 g
• C. 1920 g
• D. 680 g

Answer: (A)

Verified step by step guidance

1. Identify the conditions given: the tank volume is 855 L and the gas is nitrogen (N_2) at standard temperature and pressure (STP). Recall that STP is defined as 0°C (273 K) and 1 atm pressure.
2. Use the molar volume of an ideal gas at STP, which is 22.4 L/mol. This means 1 mole of any ideal gas occupies 22.4 liters at STP.
3. Calculate the number of moles of nitrogen gas needed to fill the tank by dividing the tank volume by the molar volume: \(\text{moles} = \frac{855\ \text{L}}{22.4\ \text{L/mol}}\).
4. Determine the molar mass of nitrogen gas (N_2). Since the atomic mass of nitrogen (N) is approximately 14.0 g/mol, the molar mass of N_2 is \$2 \times 14.0 = 28.0\ \text{g/mol}$.
5. Calculate the mass of nitrogen gas required by multiplying the number of moles by the molar mass: \(\text{mass} = \text{moles} \times 28.0\ \text{g/mol}\).