Kinetics | AQA A-Level Chemistry (7405)
Kinetics
- 133 questions
- 9 subtopics
- Physical chemistry, drawn on by Paper 1 and Paper 2
- Paper 1, Paper 2 and Paper 3
Kinetics is examined on Papers 2 and 3.
The first half explains rate qualitatively through collisions and the Maxwell-Boltzmann distribution; the second half makes it quantitative with rate equations, the Arrhenius equation, and what the rate-determining step reveals about a mechanism.
Sample questions from Kinetics
Answer each one closed book first, then open the answer.
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Collision Theory and Activation Energy
Besides having sufficient energy, what other requirement must be met for a successful collision?
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The particles must collide with the correct orientation. -
Maxwell-Boltzmann Distribution and the Effect of Temperature
How does the position of the peak of a Maxwell-Boltzmann distribution relate to the mean energy?
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The peak (most probable energy) is at a lower energy than the mean energy -
Effect of Concentration and Pressure, and Catalysts
For a gaseous reaction, what happens to the collision frequency if the pressure is halved?
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The collision frequency decreases as particles are further apart on average. -
Rate Equations: The Rate Equation and Orders of Reaction
What is the overall order of a reaction?
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The sum of the powers of the concentration terms in the rate equation -
Rate Equations: The Effect of Concentration on Rate
What happens to the rate of reaction if the concentration of a second order reactant is tripled?
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The rate increases by a factor of 9 -
The Rate Constant and the Arrhenius Equation
In the Arrhenius equation, what does A represent?
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The pre-exponential factor (or Arrhenius constant or frequency factor) -
Determining Rate Equations: The Initial Rates Method
How is the initial rate typically obtained from a concentration-time graph?
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By measuring the gradient of the tangent to the curve at time zero -
Determining Rate Equations: Continuous Monitoring
If a rate-concentration graph gives a straight line through the origin, what is the order with respect to that reactant?
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First order
The 9 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Collision Theory and Activation Energy | The two conditions a successful collision needs, and what activation energy is. | 14 |
| Maxwell-Boltzmann Distribution and the Effect of Temperature | Reading the distribution curve, and what raising the temperature does to the molecules beyond the activation energy. | 26 |
| Effect of Concentration and Pressure, and Catalysts | Collision frequency, and how a catalyst provides an alternative route of lower activation energy. | 15 |
| Rate Equations: The Rate Equation and Orders of Reaction | The form rate = k[A]ᵐ[B]ⁿ, what the rate constant means, and order with respect to a reactant and overall. | 10 |
| Rate Equations: The Effect of Concentration on Rate | What doubling or tripling a concentration does to the rate at zero, first and second order. | 12 |
| The Rate Constant and the Arrhenius Equation | The units of k, and using the Arrhenius equation and its logarithmic form. | 20 |
| Determining Rate Equations: The Initial Rates Method | Finding orders by comparing initial rates across experiments where one concentration is changed at a time. | 9 |
| Determining Rate Equations: Continuous Monitoring | Following one reaction throughout, taking gradients from the concentration-time graph, and using half-lives. | 12 |
| Rate Equations and Reaction Mechanisms | The rate-determining step, and what a species appearing in the rate equation tells you. | 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.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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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.
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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
AQA A-Level Chemistry Active Recall Guide
Every topic, not just this one. 2,442 questions with their answers.