Kinetics II | Edexcel A-Level Chemistry (9CH0)
Kinetics II
- 74 questions
- 4 subtopics
- Paper 2: advanced organic and physical chemistry
- Paper 2 and Paper 3
Covers rate equations and orders, determining an order by experiment, what a rate equation says about the mechanism, and the Arrhenius relationship..
It covers rate equations, orders and the rate constant, determining orders from experiments, rate-determining step and mechanisms and arrhenius equation and activation energy.
Sample questions from Kinetics II
Answer each one closed book first, then open the answer.
-
Rate equations, orders and the rate constant
What is the rate constant, k?
Show the answer
The proportionality constant in the rate equation linking rate to the reactant concentrations. -
Rate equations, orders and the rate constant
What are the units of the rate constant for a first-order reaction overall?
Show the answer
s⁻¹. -
Determining orders from experiments
What is the shape of a rate-concentration graph for a first-order reaction?
Show the answer
A straight line through the origin. -
Determining orders from experiments
In the iodine clock of Core Practical 13b, what is the role of the small, fixed amount of sodium thiosulfate?
Show the answer
It immediately turns the iodine formed back into iodide ions. Once it is used up, free iodine reacts with the starch and the blue-black colour suddenly appears. -
Rate-determining step and mechanisms
What does the zero order with respect to iodine in the iodination of propanone show?
Show the answer
Iodine plays no part in the slowest step. -
Rate-determining step and mechanisms
What are the orders with respect to propanone and to hydrogen ions in the acid-catalysed iodination of propanone?
Show the answer
First order with respect to propanone and first order with respect to hydrogen ions. -
Arrhenius equation and activation energy
What does the gradient of a graph of ln k against 1/T equal?
Show the answer
−Eₐ/R. -
Arrhenius equation and activation energy
In Core Practical 14, what is the role of the phenol in the reaction mixture?
Show the answer
It reacts with the bromine as it forms, C₆H₅OH + 3Br₂ → C₆H₂Br₃OH + 3HBr, so the time measured is the time for a fixed amount of bromine to be produced.
The 4 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Rate equations, orders and the rate constant | Recall questions on writing a rate equation, on what zero, first and second order mean, and on the units of the rate constant. | 12 |
| Determining orders from experiments | The initial rate and continuous monitoring methods, deducing orders from initial rates, half-lives and rate-concentration graphs, techniques for following a rate, Core Practical 13a on the iodination of propanone, the iodine clock of Core Practical 13b, and finding k for a zero-order reaction. | 29 |
| Rate-determining step and mechanisms | Recall questions on what the rate equation reveals about the slowest step, on testing a proposed mechanism against it, and on the iodination of propanone. | 18 |
| Arrhenius equation and activation energy | The Arrhenius equation and its logarithmic form, plotting ln k against 1/T to find the activation energy from the gradient and ln A from the intercept, and Core Practical 14 timing the bromate(V) and bromide reaction at several temperatures. | 15 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
-
Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
-
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
-
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
Edexcel A-Level Chemistry Active Recall Guide
Every topic, not just this one. 1,534 questions with their answers.