Based on the mole ratios in the balanced equation 2H2 + O2 → 2H2O, how many moles of H2O are produced when 4 moles of H2 react completely with excess O2?

• A. 2 moles
• B. 4 moles
• C. 1 mole
• D. 8 moles

Answer: (B)

Verified step by step guidance

1. Identify the balanced chemical equation: \$2H_2 + O_2 \rightarrow 2H_2O$.
2. Note the mole ratio between hydrogen gas (\(H_2\)) and water (\(H_2O\)) from the balanced equation. For every 2 moles of \(H_2\), 2 moles of \(H_2O\) are produced.
3. Set up a proportion based on the mole ratio: if 2 moles of \(H_2\) produce 2 moles of \(H_2O\), then 4 moles of \(H_2\) will produce \(x\) moles of \(H_2O\).
4. Write the proportion as \(\frac{2 \text{ moles } H_2O}{2 \text{ moles } H_2} = \frac{x \text{ moles } H_2O}{4 \text{ moles } H_2}\).
5. Solve for \(x\) by cross-multiplying and dividing to find the number of moles of \(H_2O\) produced when 4 moles of \(H_2\) react completely.