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JAMB Chemistry 2007 Question 7

Question 7

Rates of Reaction

Na2S2O3(aq) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + SO2(g) + S(s)
Which of the following would introduce the greatest increase in the rate of the chemical reaction above?

  1. A.An increase in temperature and a decrease in the concentration of the reactants.
  2. B.A decrease in volume and an increase in the pressure of the reactants.
  3. C.A decrease in temperature and an increase in the concentration of the reactants.
  4. D.An increase in temperature and an increase in the concentration of the reactants.
Show the answer and explanation

Answer: D (An increase in temperature and an increase in the concentration of the reactants.)

Explanation

Raising the temperature and the concentration both make collisions more frequent and more energetic, so together they give the greatest increase in rate. Pressure has little effect because the reactants are in solution.