Topic: Solubility of substances

Target group

Elementary school student (grades 7. and 8.)

Core curriculum

Elementary school. Chemistry.

V. Water and aqueous solutions. Student:

5) defines the term solubility; gives the difference between saturated and unsaturated solution;
6) reads the solubility of substances from the solubility table or from the solubility plot; calculates the mass of the substance that can be dissolved in a given amount of water at the given temperature.

General aim of education

The student discusses the influence of factors on the amount of dissolved substance in water.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to list and discuss factors affecting the solubility of the substance.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• exposing

  • film.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

3. Health and safety – before starting the experiments, students familiarise themselves with the safety data sheets of the substances that will be used during the lesson. The teacher points out the need to be careful when working with them.

Realization

1. The teacher introduces students to the problem of solubility, starting from the statement that water in nature does not occur in the pure form of a chemical compound with the formula HIndeks dolny 2₂O, but contains a lot of different substances dissolved in it. In order to remind you, the teacher asks students to explain what the solution is and what the solute and solvent are. He recommends showing examples of solutions from the home environment. A brief reminder of the information about the factors affecting the rate of dissolution of the substance, the types of solutions due to the size of the molecules of the solute: proper solution, colloidal solution and suspension - a talk.

2. The teacher announces a movie titled „Are all substances dissolved in water to the same extent?”. He instructs his students to write a research question and a hypothesis in the form provided in the abstract. Then he plays the video and the students note their observations and conclusions. The teacher encourages young people to discuss, referring to their inferences.

3. The teacher conducts - in the form of a show - an experiment, according to the instructions in the abstract (Experiment 1: „The influence of temperature on the dissolution of a solid in water on the example of sodium chloride”). Before joining the action, he asks the students to formulate a research question and a hypothesis and write them in the form in an abstract. After the experiment, a summary of observations and conclusions is made, which should also be included in the form.

4. The teacher conducts - in the form of a show - an experiment, according to the instructions in the abstract (Experiment 2: „The influence of temperature on the dissolution of gases in water on the example of carbon dioxide”). As previously, before joining the action, he asks the students to formulate a research question and a hypothesis and write them in the form in an abstract. After the experiment, a summary of observations and conclusions is made, which should also be included in the form. The teacher can refer to such a dependence occurring in nature in this place, for example in small water reservoirs on hot summer days, fish are sunk because water becomes less oxygenated. Fish stew and float to the surface. Another example is the left bottle of carbonated water / carbonated drink in a sunny place - it can crack due to too high gas pressure in the upper part of the bottle - a talk.

5. The teacher summarizes the experiments and asks the students the question: „What affects the solubility of substances in water?”.

6. Students, working individually or in pairs, carry out interactive exercises to check and consolidate knowledge learned during the lesson. Selected people discuss the correct solutions for interactive exercises. The teacher completes or straightens the statements of the proteges.

Summary

1. Students get acquainted with the content of the glossary and explain in own words the meaning of selected concepts.

2. Teacher asks: If there was going to be a test on the material we have covered today, what questions do you think would you have to answer? If the students do not manage to name all the most important questions, the teacher may complement their suggestions.

Homework

1. Make at home a note from the lesson using the sketchnoting method.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Solubility of substances

The amount of substance that can be dissolved in water depends on the temperature. In the case of gases, this quantity decreases with the increase of temperature, while for solids the amount generally increases.

• Different amounts of various substances dissolve in the same volume of water.

• The amount of solid dissolved in water depends on the temperature and usually increases with the rise of temperature.

• As the temperature rises, the amount of gas dissolved in the water decreases.