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JAMB Chemistry 1989 Question 18

Question 18

Volumetric Analysis

Using 50 cm3 of 1 M potassium hydroxide and 100 cm3 of 1 M tetraoxosulphate (VI) acid, calculate the respective volumes in cm3 of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (IV). [K = 39, S = 32, O = 16, H = 1]

  1. A.50,50
  2. B.25,50
  3. C.50,25
  4. D.25,25
Show the answer and explanation

Answer: C (50,25)

Explanation

2KOH + H2SO4 → K2SO4 + 2H2O. The most salt comes from using all the base: 50 cm3 of 1 M KOH (0.05 mol) needs 0.025 mol acid, which is 25 cm3.