Consider the reaction: N2 + 3H2 → 2NH3. How many grams of N2 are required to produce 100.0 L of NH3 at STP?

• A. 56.0 g
• B. 83.6 g
• C. 28.0 g
• D. 41.8 g

Answer: (B)

Verified step by step guidance

1. Identify the given information and what is asked: You are given the volume of NH\_3 gas (100.0 L) at STP and need to find the mass of N\_2 required to produce this amount of NH\_3.
2. Recall that at STP (Standard Temperature and Pressure), 1 mole of any ideal gas occupies 22.4 L. Use this to convert the volume of NH\_3 to moles using the formula: \(\text{moles of NH}_3 = \frac{\text{volume of NH}_3}{22.4\,\text{L/mol}}\).
3. Use the balanced chemical equation \(\mathrm{N}_2 + 3\mathrm{H}_2 \rightarrow 2\mathrm{NH}_3\) to find the mole ratio between N\_2 and NH\_3. From the equation, 1 mole of N\_2 produces 2 moles of NH\_3. Use this ratio to calculate moles of N\_2 needed: \(\text{moles of N}_2 = \frac{1}{2} \times \text{moles of NH}_3\).
4. Calculate the mass of N\_2 using its molar mass. The molar mass of N\_2 is approximately 28.0 g/mol. Use the formula: \(\text{mass of N}_2 = \text{moles of N}_2 \times 28.0\,\text{g/mol}\).
5. Combine all the steps to find the mass of N\_2 required to produce 100.0 L of NH\_3 at STP without calculating the final number.