Chemistry Year 11 - Module 1 - Lesson 3
Filtration and Crystallisation
1. Key Ideas
In the 9th century, Arab chemist Jabir ibn Hayyan devised systematic methods for purifying substances — including filtration and crystallisation. His techniques, refined over 1200 years, are still used in every chemistry laboratory in the world today.
- The principle behind filtration and crystallisation
- Why particle size determines whether filtration works
2. Success Criteria
By the end, you should be able to:
- The principle behind filtration and crystallisation
- The key equipment used in each technique
- Which mixture types each technique is suited for
3. Key Terms
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. 6. Describe the principle of filtration and explain why it cannot be used to separate sodium chloride from a sodium chloride solution.
2. 7. A student dissolves 80 g of potassium chloride in 100 mL of hot water, then allows the solution to cool to room temperature. They observe crystals forming. Explain why crystals form on cooling, referring to solubility and saturation.
3. 8. A chemist has a sample of impure table salt (NaCl with some coloured pigment impurities that are also soluble in water). Evaluate whether a single crystallisation step will produce chemically pure NaCl, and suggest how the chemist could improve the purity of their final product.
6. Extend: Apply the Idea
A student gives a memorised answer about Filtration and Crystallisation 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 Filtration and Crystallisation?
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 Filtration and Crystallisation?
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.