AQA A-Level Chemistry Paper 3, 2023: Question 11

1 mark · Easy difficulty · Multiple Choice

Maxwell–Boltzmann Distribution Curve Question This question relates to the Maxwell–Boltzmann distribution of particle energies in a gaseous reactant, asking what the total area under the curve represents.

Practise this question

Question

AQA A-Level Chemistry Paper 3, 2023: Question 11
Question text

11 This is a Maxwell–Boltzmann distribution for a gaseous reactant.

What is represented by the total area under the curve?

[1 mark]

A total energy of the particles

B activation energy for the reaction

C total number of reacting particles

D total number of particles present

Mark scheme

Show the mark scheme Mark scheme for AQA A-Level Chemistry Paper 3, 2023: Question 11

11 D 1 (AO1) total number of particles present

How to answer it

Understanding the Maxwell-Boltzmann Distribution

Question

What is represented by the total area under the curve?

  • A: Total energy of the particles
  • B: Activation energy for the reaction
  • C: Total number of reacting particles
  • D: Total number of particles present

Correct Answer: D

The total area under a Maxwell-Boltzmann distribution curve represents the total number of particles present in the system.

Teacher Tip: The area does not depend on temperature or energy distribution—it simply accounts for the total particle count. Focus on interpreting the curve correctly to avoid common pitfalls.

Explanation of Other Options

  • A: The total energy is not represented by the area; the curve's shape shows the distribution of energies.
  • B: The activation energy is marked as a specific point on the x-axis, not the area under the curve.
  • C: Only particles with energy greater than the activation energy contribute to a reaction, but the total area under the curve includes all particles.
Teacher Tip: For questions involving energy distributions, remember that the curve's shape shows the energy spread, while the area represents the total particles.

Key Characteristics of the Maxwell-Boltzmann Curve

The Maxwell-Boltzmann curve illustrates the distribution of particle energies in a gas. Key features include:

  • A peak representing the most probable energy.
  • A long tail indicating particles with very high energy.
  • The total area under the curve remains constant as it represents the total number of particles.

Final Answer

The correct representation of the total area under the Maxwell-Boltzmann curve is:

D: Total number of particles present

Topics

Physical Chemistry · 3.1.5 Kinetics

Question and mark scheme from the AQA A-Level Chemistry examination, Paper 3, 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.