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JAMB Chemistry 1998 Question 27

Question 27

Energy Changes

32g of anhydrous copper (II) tetraoxosulphate (VI) dissolved in 1dm3 of water generated 13.0kJ of heat. The heat of solution is [Cu = 64, S = 32, O = 16]

  1. A.26.0 kJmol−1
  2. B.65.0 k Jmol−1
  3. C.130.0 kJmol−1
  4. D.260.0kJmol−1
Show the answer and explanation

Answer: B (65.0 k Jmol−1)

Explanation

Molar mass of CuSO4 = 160, so 32 g = 0.2 mol. Heat per mole = 13.0/0.2 = 65.0 kJ mol−1 (given out, so ΔH = −65 kJ mol−1).