Engineering Board Exam Reviewer · Chemistry · hard

10 g of H2 reacts with 64 g of O2 (2 H2 + O2 2 H2O). Which is the limiting reactant, and how much water forms? (Use H = 1, C = 12, N = 14, O = 16, Na = 23, S = 32, Cl = 35.5, Ca = 40)

Answer

B. O2 is limiting; 72 g of water

n(H2) = 5 mol; n(O2) = 2 mol needs 4 mol H2 O2 is limiting. Water = 2 × 2 = 4 mol × 18 = 72 g (1 mol H2 is left over).

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