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JAMB Chemistry 1987 Question 25

Question 25

Alkanoic Acids and Esters

Z is a solid substance which liberates carbon (IV) oxide on treatment with concentrated H2SO4. A warm solution of Z also decolorizes acidified KMnO4. The solid substance, Z, is

  1. A.sodium hydrogen trioxocarbonate (IV)
  2. B.methanoic acid
  3. C.iron (II) trioxocarbonate (IV)
  4. D.ethanedioic acid (oxalic acid).
Show the answer and explanation

Answer: D (ethanedioic acid (oxalic acid).)

Explanation

Concentrated H2SO4 dehydrates solid oxalic acid to CO and CO2, and warm oxalic acid is oxidised by KMnO4, decolourising it. Methanoic acid is a liquid and NaHCO3 is not a reducing agent.