In the reaction 2 H2 + O2 → 2 H2O, how many moles of water are produced when 4 moles of hydrogen gas react completely with excess oxygen gas?

• A. 2 moles
• B. 8 moles
• C. 6 moles
• D. 4 moles

Answer: (B)

Verified step by step guidance

1. Identify the balanced chemical equation: \$2 \text{H}_2 + \text{O}_2 \rightarrow 2 \text{H}_2\text{O}$.
2. Note the mole ratio between hydrogen gas (\(\text{H}_2\)) and water (\(\text{H}_2\text{O}\)) from the balanced equation, which is 2 moles of \(\text{H}_2\) produce 2 moles of \(\text{H}_2\text{O}\).
3. Set up a proportion to find the moles of water produced from 4 moles of hydrogen gas using the mole ratio: \(\frac{2 \text{ moles } \text{H}_2\text{O}}{2 \text{ moles } \text{H}_2} = \frac{x \text{ moles } \text{H}_2\text{O}}{4 \text{ moles } \text{H}_2}\).
4. Solve the proportion for \(x\) to find the moles of water produced.
5. Interpret the result as the number of moles of water formed when 4 moles of hydrogen gas react completely with excess oxygen.