How many moles of oxygen gas (O_2) are required to react completely with hydrogen gas (H_2) to produce 12 moles of water (H_2O)?

• A. 24 moles
• B. 12 moles
• C. 6 moles
• D. 3 moles

Answer: (C)

Verified step by step guidance

1. Write the balanced chemical equation for the reaction between hydrogen gas and oxygen gas to form water: \$2H_2 + O_2 \rightarrow 2H_2O$.
2. Identify the mole ratio between oxygen gas (\(O_2\)) and water (\(H_2O\)) from the balanced equation. For every 2 moles of \(H_2O\) produced, 1 mole of \(O_2\) is required.
3. Set up a proportion to find the moles of \(O_2\) needed to produce 12 moles of \(H_2O\): \(\frac{1 \text{ mole } O_2}{2 \text{ moles } H_2O} = \frac{x \text{ moles } O_2}{12 \text{ moles } H_2O}\).
4. Solve for \(x\) (the moles of \(O_2\) required) by cross-multiplying and dividing: \(x = \frac{1}{2} \times 12\).
5. Interpret the result as the number of moles of oxygen gas needed to react completely with hydrogen gas to produce 12 moles of water.