Chemistry Year 11 - Module 2 - Lesson 8

Concentration in Context

Use this worksheet after reading the lesson to practise the key ideas and prove you can meet the success criteria.

Name

Date

Class

1. Key Ideas

You can do every concentration calculation perfectly on paper and still fail an exam question — because the numbers are wrapped in a real-world scenario you don't recognise. This lesson teaches you to strip away the context, find the numbers, and apply the formulas you already know. That's the skill that separates 70% students from 90% students.

% purity formula and what it means
Why impurities reduce the actual moles present

2. Success Criteria

By the end, you should be able to:

% purity formula and what it means
Realistic concentration ranges for common substances
How purity adjusts the mass you need to weigh

3. Key Terms

MoleThe SI unit for amount of substance; contains exactly 6.022 × 10²³ particles.

Avogadro's Number6.022 × 10²³ — the number of particles in one mole of a substance.

Molar MassThe mass of one mole of a substance, measured in g/mol.

Limiting ReagentThe reactant that is completely consumed first, limiting the amount of product formed.

Empirical FormulaThe simplest whole-number ratio of atoms in a compound.

Molecular FormulaThe actual number of atoms of each element in a molecule of a compound.

4. Activity: Build the Lesson Map

Use the lesson to complete the table. Keep answers brief but specific.

Prompt	Your answer
Main concept
Important example
Common mistake to avoid
How this links to the next lesson

5. Short Answer Questions

1. Explain this lesson goal in your own words: "% purity formula and what it means". Use one specific example from the lesson.

Band 32 marks

2. Apply this idea to a new example: "Realistic concentration ranges for common substances". Show your reasoning clearly.

Band 43 marks

3. Analyse why this idea matters for understanding Concentration in Context: "How purity adjusts the mass you need to weigh".

Band 54 marks

6. Extend: Apply the Idea

Band 5/65 marks

A student gives a memorised answer about Concentration in Context but does not use evidence or reasoning.

Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.

7. Multiple Choice

1. What is the best first step when answering a question about Concentration in Context?

A. Identify the key concept being tested

B. Write every fact from memory

C. Ignore the command word

D. Skip examples and evidence

2. Which answer would show stronger understanding of Concentration in Context?

A. An answer with accurate terms and reasoning

B. A copied definition only

C. A single-word response

D. An answer with no example

3. What should you do if a question asks you to explain?

A. Link the idea to a reason or cause

B. List unrelated facts

C. Only draw a diagram

D. Write the shortest possible answer

8. Success Criteria Proof

Finish with evidence that you can do each success criterion.

Success criterion 1

Prove that you can: % purity formula and what it means