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JAMB Chemistry 1983 Question 36

Question 36

Mole Concept and Stoichiometry

2.5 g of a hydrated barium salt gave on heating, 2.13 g of the anhydrous salt. Given that the relative molecular mass of the anhydrous salt is 208, the number of molecules of water of crystallization of the barium salt is

  1. A.10
  2. B.7
  3. C.5
  4. D.2
  5. E.1.
Show the answer and explanation

Answer: D (2)

Explanation

Anhydrous salt = 2.13/208 = 0.0102 mol; water = 0.37 g = 0.0206 mol. 0.0206/0.0102 ≈ 2, so the formula is BaCl2.2H2O.