Solubility | Developing understanding | 14–16 years | Resource

No comments

Encourage learners to think about how graphical representations of solubility link to macroscopic observations and symbolic understanding

Developing understanding is a series of resources that encourages learners to connect their thinking at the macroscopic, sub-microscopic and symbolic levels.

Download this

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

Download All

View and download more Developing understanding worksheets

Learning objectives

Recognise that a substance may be soluble in one solvent but insoluble in another.
Identify whether a substance is soluble or insoluble from macroscopic observations.
Use solubility to explain macroscopic observations.
Recognise that the solubility of a substance can change with temperature.
Interpret different points on a temperature–solubility graph.
Connect points on a temperature-solubility graph with macroscopic observations.

How to use this resource

This resource aims to develop learners’ understanding of solubility. The questions encourage learners to think about how graphical representations of solubility link to macroscopic observations and symbolic understanding. 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, sub-microscopic and symbolic. You can use Johnstone’s triangle to build a secure understanding of chemical ideas for your learners.

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 as an in-class activity it is best to pause and check understanding at intervals, as often one question builds on the previous one.

It is useful for learners to observe macroscopic properties first-hand. You could circulate examples of substances in the classroom, run a class practical of a chemical reaction or show a teacher demonstration of properties.

Additional support may be needed for any learners still lacking in confidence in the required symbolic representation, for example by sharing and explaining a diagram or a simulation that can show movement of the particles.

Answers and guidance

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

Question one supports learners to recognise that a solvent does not have to be water and that a substance may be insoluble in one liquid but soluble in another (macroscopic understanding). This question assumes that learners are already familiar with the terms soluble and insoluble.

Question two supports learners to recognise observations (macroscopic understanding) that show that a substance is soluble (formation of a clear solution) or insoluble (either a lump of undissolved solid or a cloudy mixture formed by a powder that does not dissolve).

If learners need support explain that:

If the substance is soluble in the solvent then it will seem to disappear and the solution will remain clear i.e. you can see through it. The solution may be colourless or coloured.
If the substance is insoluble, then it will either sink to the bottom or make the solution cloudy when first added.

Question 3 supports learners explain observations (macroscopic understanding) in terms of the solubility of a compound.

Question 4 supports further understanding of the graphical representation (a form of symbolic understanding) of solubility of a compound at different temperatures. It then develops learners’ ability to connect this with observations (macroscopic understanding).

The first part of question 5 supports learners to explain observations (macroscopic understanding) in terms of the change in solubility of a compound at different temperatures. The second part of the question supports learners to interpret the meaning of a graphical representation (a form of symbolic understanding) of solubility of a compound at different temperatures. This question assumes some familiarity with the interpretation of a graph. Learners lacking confidence with this may require additional scaffolding and support.