Chemistry Unit 4 Question Paper for Edexcel International A Level focuses on rates, equilibria, and further organic chemistry. This exam paper includes various questions designed to assess students’ understanding of chemical principles and their application in different scenarios. Ideal for students preparing for their chemistry examinations, it covers essential topics such as reaction rates, equilibrium constants, and organic reaction mechanisms. The paper is structured to challenge students’ analytical and problem-solving skills in chemistry.

Key Points

  • Includes questions on reaction rates and chemical equilibria
  • Covers further organic chemistry topics relevant to the syllabus
  • Designed for Edexcel International A Level chemistry students
  • Tests understanding through a variety of question formats
Dandeldew
32 pages
Language:English
Type:Past Paper
Chemistry
Dandeldew
32 pages
Language:English
Type:Past Paper
Chemistry
201
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P78829A
©2025 Pearson Education Ltd.
M:1/1/1/1/
Please check the examination details below before entering your candidate information
Candidate surname Other names
Centre Number Candidate Number
Pearson Edexcel International Advanced Level
Wednesday 22 October 2025
Afternoon (Time: 1 hour 45 minutes)
WCH14/01
Paper
reference
Total Marks
Chemistry
International Advanced Level
UNIT 4: Rates, Equilibria and Further
OrganicChemistry
You must have:
Scientific calculator, Data Booklet
Instructions
•
Use black ink or ball-point pen.
•
If pencil is used for diagrams/sketches/graphs it must be dark (HB or B).
•
Fill in the boxes at the top of this page with your name,
centre number and candidate number.
•
Answer all questions.
•
Answer the questions in the spaces provided
– there may be more space than you need.
Information
•
The total mark for this paper is 90.
•
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
•
In the question marked with an asterisk (*), marks will be awarded for your ability
to structure your answer logically, showing how the points that you make are
related or follow on from each other where appropriate.
•
A Periodic Table is printed on the back cover of this paper.
Advice
•
Read each question carefully before you start to answer it.
•
Show all your working in calculations and include units where appropriate.
•
Try to answer every question.
•
Check your answers if you have time at the end.
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2
SECTION A
Answer ALL the questions in this section.
You should aim to spend no more than 20 minutes on this section.
For each question, select one answer from A to D and put a cross in the box
. If you change
your mind, put a line through the box
and then mark your new answer with a cross .
1 Nitrogen dioxide, NO
2
, is produced in the reaction shown.
2NO(g) + O
2
(g) → 2NO
2
The table shows the results of a series of experiments to measure the initial rate of
this reaction at 298 K.
Experiment
number
Initial concentration / mol dm
–3
Initial rate
/ mol dm
–3
s
–1
[NO] [O
2
]
1 0.0125 0.0050 5.10 × 10
–4
2 0.0125 0.0100 10.2 × 10
–4
3 0.0250 0.0200 81.6 × 10
–4
What are the orders of reaction with respect to NO and O
2
?
NO O
2
A first order first order
B second order first order
C first order second order
D second order second order
(Total for Question 1 = 1 mark)
Use this space for any rough working. Anything you write in this space will gain no credit.
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2 A series of experiments was carried out to determine the effect of temperature on the
rate of the reaction between peroxodisulfate ions and iodide ions.
S
2
O
8
2–
+ 2I
–
→ 2SO
4
2–
+ I
2
A student plotted a graph of ln k against 1 ÷ T and used the gradient of the line of
bestfit to determine the activation energy, E
a
, using the Arrhenius equation.
ln k = –
E
RT
a
+ a constant
The graph is shown.
2.7 × 10
–4
–1.23
0.0029 0.0030 0.0031 0.0032 0.0033
0.0034
–3.00
–3.50
–4.00
–4.50
–5.00
–5.50
l
n k
1 ÷ T / K
–1
Which is the expression for the activation energy for this reaction?
A – (–1.23 ÷ 2.7 × 10
–4
) × 8.31
B

4
(1.232.7 10 )
8.31
C – (2.7 × 10
–4
÷ –1.23) × 8.31
D

4
(2.7 10 1.23)
8.31
(Total for Question 2 = 1 mark)
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FAQs

what topics are covered in the Chemistry Unit 4 Question Paper - Edexcel International A Level?

The Chemistry Unit 4 Question Paper - Edexcel International A Level covers several key topics essential for understanding advanced chemistry concepts.

  • Rates of reaction
  • Equilibria
  • Further organic chemistry
  • Thermodynamics
  • Reaction mechanisms

how to prepare for the Chemistry Unit 4 Question Paper - Edexcel International A Level?

Preparing for the Chemistry Unit 4 Question Paper - Edexcel International A Level requires a structured approach to studying.

  • Review the syllabus and key concepts.
  • Practice past papers to familiarize yourself with the question format.
  • Focus on understanding reaction mechanisms and equilibrium concepts.
  • Utilize study groups for collaborative learning.
  • Consult textbooks and online resources for additional explanations.

what is the format of the Chemistry Unit 4 Question Paper - Edexcel International A Level?

The Chemistry Unit 4 Question Paper - Edexcel International A Level typically consists of multiple sections.

  • Section A: Short answer questions
  • Section B: Longer, structured questions
  • Data analysis and interpretation tasks
  • Practical application questions

what types of questions are in the Chemistry Unit 4 Question Paper - Edexcel International A Level?

The Chemistry Unit 4 Question Paper - Edexcel International A Level includes various types of questions to assess different skills.

  • Multiple choice questions
  • Short answer questions
  • Calculation-based questions
  • Data interpretation questions
  • Extended response questions requiring detailed explanations

what are the key formulas for Chemistry Unit 4 - Edexcel International A Level?

Key formulas for the Chemistry Unit 4 - Edexcel International A Level include important equations related to reaction rates and equilibria.

  • Rate = k[A]^n[B]^m (Rate law)
  • Kc = [products]/[reactants] (Equilibrium constant)
  • ΔG = ΔH - TΔS (Gibbs free energy)
  • pH = -log[H+] (pH calculation)

how is the Chemistry Unit 4 Question Paper - Edexcel International A Level graded?

The Chemistry Unit 4 Question Paper - Edexcel International A Level is graded based on a combination of accuracy and understanding.

  • Marks are awarded for correct answers and clear reasoning.
  • Structure and clarity of explanations are also considered.
  • Practical skills may be assessed through related questions.

what are common mistakes in the Chemistry Unit 4 Question Paper - Edexcel International A Level?

Common mistakes in the Chemistry Unit 4 Question Paper - Edexcel International A Level often stem from misunderstanding key concepts.

  • Misapplying equilibrium expressions.
  • Incorrectly balancing chemical equations.
  • Failing to show all working in calculations.
  • Neglecting units in answers.

what is the importance of practical skills in the Chemistry Unit 4 Question Paper - Edexcel International A Level?

Practical skills are crucial in the Chemistry Unit 4 Question Paper - Edexcel International A Level as they demonstrate understanding of theoretical concepts.

  • They enhance the ability to conduct experiments accurately.
  • Practical skills help in analyzing data and drawing conclusions.
  • They prepare students for real-world applications of chemistry.

how to analyze data in the Chemistry Unit 4 Question Paper - Edexcel International A Level?

Analyzing data in the Chemistry Unit 4 Question Paper - Edexcel International A Level involves several key steps.

  • Identify trends and patterns in the data.
  • Use appropriate calculations to interpret results.
  • Compare findings with theoretical expectations.
  • Draw conclusions based on the analysis.

what are the best resources for studying Chemistry Unit 4 - Edexcel International A Level?

Effective resources for studying Chemistry Unit 4 - Edexcel International A Level include a variety of materials.

  • Textbooks specific to the Edexcel syllabus.
  • Online tutorials and video lectures.
  • Past exam papers and mark schemes.
  • Study guides and revision notes.