Water sample analysis: distillation
Lesson details
Learning outcome
I can use distillation to purify water samples and analyse the distillate to test its purity.
Key learning points
- Distillation can be used to purify water samples.
- Boiling point data can be analysed to assess the purity of water samples.
- The more impurities present in a sample, the larger the temperature range over which the water will boil.
- Pure water boils at 100°C.
Keywords
Impurity - A chemical that is found in a material in very small amounts, but can change the material's properties.
Pure - A single element or compound that is not mixed with any other substance.
Sample - A smaller portion of a larger quantity of a substance.
Distillation - A separation technique that uses boiling and condensation to remove and isolate a liquid component of a mixture.
Distillate - The liquid that is condensed from the gas state during distillation.
Common misconception
All water samples boil at 100°C.
If a water sample is impure, the boiling point of water increases. The greater the amount of impurities in a water sample, the larger the temperature range over which it boils.
Teacher tip
Ensure the end of the delivery tube is kept out of the distillate to avoid 'suck back' and loss of distillate. Include ice in the 'beaker water bath' to improve condensation. Consider extending the practical by including rain water / mineral water samples.
Equipment
Quickfit apparatus (or conical flask, test tube, delivery tube, ice, beaker, tripod, gauze), thermometer, Bunsen Burner, heatproof mat, sample of 'sea water'.
Licence
except where otherwise stated. See Oak's terms & conditions (Collection 2).Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is the main principle behind the separation of mixtures in distillation?
Q2.Why can't filtration separate soluble substances from liquids?
Q3.What does a change in the boiling point of a liquid indicate?
Q4.What does filtration separate?
Q5.What is condensation?
Q6.How can boiling point data be used?
Assessment exit quiz
6 Questions
Q1.What process would produce pure water from potable water containing dissolved solids?
Q2.What does a boiling point range of 98°C to 102°C suggest about the water sample?
Q3.What is indicated by a boiling point of 100°C?
Q4.What is the purpose of the condenser in the distillation apparatus?
Q5.Why is it important to collect the distillate in a clean container?
Q6.How can you determine the effectiveness of distillation from boiling point data?
To help you plan your 10 chemistry lesson on: Water sample analysis: distillation, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 chemistry lesson on: Water sample analysis: distillation, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 chemistry lessons from the Separating substances unit, dive into the full secondary chemistry curriculum, or learn more about lesson planning.