For N₂ + 3H₂ → 2NH₃, 56 g of N₂ is mixed with 18 g of H₂. What is the maximum mass of NH₃ that can form? (Relative atomic masses: H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Zn = 65.)
Answer and explanation
Correct answer: A. 68 g
- Step 1: There are 2 mol of N₂ and 9 mol of H₂; the ratio needed is 1 : 3, so the limiting reactant is N₂.
- Step 2: N₂ gives at most 4 mol of NH₃.
- Step 3: Mass = 4 x 17 = 68 g.
Answer
68 g.
Why not the others: 102 g: only H₂ was used, without checking whether the N₂ is enough. 74 g: the masses of the reactants were added. 34 g: the coefficient 2 was left out when converting to grams.
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