Evaporation and distillation | Developing understanding | 11–14 years | Resource

No comments

This resource aims to develop learners’ understanding of evaporation and distillation.

Download this

A ramped worksheet to help learners develop their mental models of evaporation and distillation. With icons to indicate the conceptual level/s of each question.

Download All

View and download more Developing understanding worksheets

Learning objectives

Explain the gradual evaporation of a puddle of water in terms of particles.
Link surface area to rate of evaporation.
Explain the separation of a solution using evaporation.
Describe the changes of state of water that occur during distillation.
Explain observations of the distillation of a coloured solution.

How to use this resource

This resource aims to develop learners’ understanding of evaporation and distillation. The questions encourage learners to explain observations of distillation in terms of particles and to think carefully about what is happening at each stage of the distillation process. As a result, learners should develop more secure mental models to support their thinking about this topic.

When to use? Use after initial teaching or discussion of this topic to develop ideas further. You can also use as a revision activity.
Group size? Suitable for independent work either in class or at home. Or use the questions for group or class discussions.
How long? 15–30 mins

Johnstone’s triangle

Johnstone’s triangle is a model of the three different conceptual levels in chemistry: macroscopic, symbolic and sub-microscopic. You can use Johnstone’s triangle to build a secure understanding of chemical ideas for your learners.

Introduce learners to Johnstone’s triangle with our Distilling copper sulfate solution Johnstone’s triangle worksheet which guides learners to think about distillation apparatus in the context of copper sulfate solution.

Johnstone’s triangle and this resource

The icons in the margin indicate which level of understanding each question is developing to help prompt learners in their thinking.

Macroscopic: what we can see. Think about the properties that we can observe, measure and record.
Sub-microscopic: smaller than we can see. Think about the particle or atomic level.
Symbolic: representations. Think about how we represent chemical ideas including symbols and diagrams.

The levels are interrelated, for example, learners need visual representation of the sub-microscopic in order to develop mental models of the particle or atomic level. Our approach has been to apply icons to questions based on what the learners should be thinking about.

Questions may be marked with two or all three icons, indicating that learners will be thinking at more than one level. However, individual parts of the question may require learners to think about only one or two specific levels at a time.

Support

This worksheet is ramped so that the earlier questions are more accessible. The activity becomes more challenging in the later questions. You can give extra explanations for the more challenging questions. If completing this worksheet as an in-class activity, it is best to pause and check understanding at intervals, as often one question builds on the previous one.

Answers and guidance

There are five multi-part questions in the student worksheet. The answers can be found in the teacher notes.

The first question develops learners’ understanding by connecting everyday observations of a puddle ‘drying’ (macroscopic understanding) to a particle-level explanation (sub-microscopic understanding).

The second question develops learners’ understanding of how evaporation occurs faster when there is a greater surface area (macroscopic understanding) and how this can be explained in terms of particles (sub-microscopic understanding).

The third question develops learners’ understanding of evaporation process by using observations of the evaporation of water from copper sulfate solution (macroscopic understanding) and encouraging learners to explain these observations using the idea of particles (sub-microscopic understanding).

The fourth question develops learners’ understanding of distillation by encouraging deeper thought about the state of water at different points in the apparatus and the changes of state that occur (macroscopic understanding).

The final question develops learners’ understanding of distillation further encouraging explanation of observations at different points of the apparatus during the distillation of blue ink and water (macroscopic understanding).