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JAMB Chemistry 1998 Question 19

Question 19

Acids, Bases and Salts

The pH of a solution obtained by mixing 100cm3 of a 0.1M HCl solution with 100cm3 of a 0.2M solution of NaOH is

  1. A.1.3
  2. B.7.0
  3. C.9.7
  4. D.12.7
Show the answer and explanation

Answer: D (12.7)

Explanation

HCl = 0.01 mol and NaOH = 0.02 mol, so 0.01 mol of OH− is left in 200 cm3: [OH−] = 0.05 M. pOH = −log 0.05 = 1.3, so pH = 14 − 1.3 = 12.7.