Which of the following will produce the greatest increase in the rate of the chemical...

JAMB 1988

Which of the following will produce the greatest increase in the rate of the chemical reaction represented by the equation Na2S2O3(aq) + 2HCl(aq) → 2NaCI(aq) + H2O(I) + SO2(g) + S(g)?

A. A decrease in temperature and an increase in the concentration of the reactants
B. An increase in the temperature and a decrease in the cocentration of the reactants
C. An increase in temperature and an increase in the concentration of the reactants
D. A decrease in the temperature and a decrease in the concentration of the reactants

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Correct Answer: Option C

Explanation

The rate of a chemical reaction is governed by the frequency and energy of collisions between reactant particles (Collision Theory). For the reaction between sodium thiosulfate( Na\(_2\)S\(_2\)O\(_3\)) and hydrochloric acid,(HCl). The rate is optimized by the following factors:

- Increasing the temperature increases the average kinetic energy of the particles.

Higher collision frequency: Particles move faster and collide more often.
Greater collision energy: A larger fraction of particles possess energy equal to or greater than the activation energy, leading to more effective collisions.

- Effect of Concentration: Increasing the concentration of the reactants increases the number of particles per unit volume.

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