Chapter: Chemical Kinetics

---

🔟 Important Questions – Chapter 4: Chemical Kinetics

1. The rate constant for a first-order reaction is 60 s⁻¹. How much time will it take to reduce the initial concentration of the reactant to its 1/16th value?

2. Show that for a first-order reaction, the time required for 99.9% completion is approximately 10 times the half-life of the reaction.

3. For a first-order reaction, show that the time required for 75% completion is twice the half-life of the reaction.

4. The decomposition of gaseous ethane follows first-order kinetics:
   C₂H₆(g) → C₂H₄(g) + H₂(g)
   The rate constant is 2.18 × 10⁻² s⁻¹ at 650°C. Calculate the concentration of C₂H₆ left after 30 minutes if the initial concentration is 0.80 mol/L.

5. Define a pseudo-first order reaction. Give one suitable example from daily life or laboratory conditions.

6. The decomposition of NH₃ on a platinum surface is a zero-order reaction. What are the units of its rate constant?

7. Write the integrated rate equation for a zero-order reaction and explain each term involved.

8. A first-order reaction is 40% complete in 50 minutes. Calculate the rate constant. What is the half-life of the reaction?

9. Write the expression for the half-life of a first-order reaction and explain why it is independent of the initial concentration.

10. How can the rate constant for a first-order reaction be determined graphically?