In the reaction 2H_2 + O_2 ightarrow 2H_2O, if 4 moles of H_2 and 2 moles of O_2 are mixed, what is the chemical formula for the limiting reactant?

• A. H_2O
• B. H_2
• C. None; both are in excess
• D. O_2

Answer: (D)

Verified step by step guidance

1. Write down the balanced chemical equation: \$2H_2 + O_2 \rightarrow 2H_2O$.
2. Identify the mole ratio of the reactants from the balanced equation: 2 moles of \(H_2\) react with 1 mole of \(O_2\).
3. Compare the given moles of each reactant to the mole ratio to find the limiting reactant. For 4 moles of \(H_2\), the required moles of \(O_2\) would be \(\frac{4}{2} = 2\) moles.
4. Since 2 moles of \(O_2\) are available and exactly needed to react with 4 moles of \(H_2\), check if either reactant is in excess by comparing actual moles to required moles.
5. Determine the limiting reactant by identifying which reactant will be completely consumed first based on the mole ratio and given amounts.