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JAMB Chemistry 1998 Question 21

Question 21

Volumetric Analysis

What volume of 0.1 mol dm−3 solution of tetraoxosulphate (VI) acid would be needed to dissolve 2.86g of sodium trioxocarbonate (IV) decahydrate crystals? [H = 1, C = 12, O = 16, S = 32, Na = 23].

  1. A.20cm3
  2. B.40cm3
  3. C.80cm3
  4. D.100cm3
Show the answer and explanation

Answer: D (100cm3)

Explanation

Na2CO3.10H2O has molar mass 286, so 2.86 g = 0.01 mol. It reacts 1 : 1 with H2SO4, so 0.01 mol of acid is needed: 0.01/0.1 = 0.1 dm3 = 100 cm3.