Chemistry

1. 1.

   Explain why crushing a solid reactant can increase its reaction rate with a solution without changing the mass used.

   [3 marks] · no calculator
2. 2.

   On a product-volume versus time graph, explain how to estimate the initial rate and why final volume is not a rate.

   [3 marks] · no calculator
3. 3.

   Doubling [A] with [B] and all other conditions constant doubles the initial rate; doubling [B] with [A] and all other conditions constant quadruples it. Determine the rate law, overall order and units of k when rate is mol dm^-3 s^-1.

   [3 marks] · no calculator
4. 4.

   For rate = k[A]^2, rate = 0.0080 mol dm^-3 s^-1 when [A] = 0.20 mol dm^-3. Calculate k and the rate at [A] = 0.30 mol dm^-3 at the same temperature.

   [3 marks]
5. 5.

   An observed rate law is rate = k[A][B]. A proposed mechanism starts with slow A + B -> X, followed by fast X + B -> P. Assess its consistency and explain why the rate law does not prove this mechanism uniquely.

   [4 marks] · no calculator
6. 6.

   A student says higher temperature speeds a reaction only because collisions happen more often. Evaluate this explanation using an energy distribution and activation energy.

   [4 marks] · no calculator

Original, unofficial practice questions from SubjectScout — not official past-paper questions.