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JAMB Chemistry 1987 Question 4

Question 4

Mole Concept and Stoichiometry

In the reaction CaC2(s) + 2H2O(l) → Ca(OH)2(s) + C2H2(g) what is the mass of solid calcium carbide needed to produce 1000 cm3 of acetylene gas at S.T.P.? [C = 12, Ca = 40, G.M.V = 22400 cm3]

  1. A.3.8 g
  2. B.2.9 g
  3. C.2.0 g
  4. D.1.0 g
Show the answer and explanation

Answer: B (2.9 g)

Explanation

1 mol CaC2 (64 g) gives 22400 cm3 of C2H2. For 1000 cm3: 64 × 1000/22400 = 2.86 g, about 2.9 g.