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For a reaction, N2(g) + 3H2(g) → 2NH3(g); identify dihydrogen (H2) as a limiting reagent in the following reaction mixtures.

1. 56 g of N2 + 10 g of H2
2. 35 g of N2 + 8 g of H2
3. 28 g of N2 + 6 g of H2
4. 14 g of N2 + 4 g of H2

Correct answer: 56 g of N2 + 10 g of H2

Solution

In the reaction, 1 mole of N2 reacts with 3 moles of H2. In option A, the amount of H2 available (10 g or about 5 moles) is insufficient to fully react with the available N2 (56 g or about 2 moles), making H2 the limiting reagent.

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