Title: Diffusion

Supplementary material for use in lessons in the group of natural sciences (nature, biology, chemistry, geography, physics), additional classes, science clubs. It can serve as a resource for expanding knowledge, preparing students for science competitions.

Lesson plan elaborated by: Zyta Sendecka

Target Group

Students of the 7th grade of primary school (chemistry).

Core Curriculum

Grade VII – chemistry

I. Substances and their properties. Student:

4) explains the phenomena of diffusion, dissolution, and change of state of matter.

The general aim of education

Students explain movements of particles in gases and liquids and they prove diffusion phenomena.

Criteria for success

• explain the term „diffusion”;

• show diffusion with a model;

• carry out experiments proving diffusion;

• demonstrate that diffusion is a very important for living organisms.

Key Competences

• Communication in the mother tongue;

• Communication in foreign languages;

• Mathematical competence and basic competences in science and technology;

• Digital competence;

• Learning to learn;

• Social and civic competences.

Methods/forms of work

Talk, work with the text, work with the film, modeling, direct observation, indirect observation.

Frontal work, individual work and work in groups.

Teaching aids

• abstract;

• interactive or traditional board;

• tablets/computers;

• set necessary to carry out the „Observation 1”: balloon, almond oil, large closed cardboard box;

• paper plates;

• small, plastic balls in two colors (equal size and weight);

• set needed to perform „Experiment 1”: three heat‑resistant glasses, stopwatch, water, teaspoon, kettle, ink (one set per group).

Before the lesson

30 minutes before classes, the teacher performs the activities necessary to carry out „Observation 1”:

• a few drops of almond oil are poured into the balloon;

• inflates the balloon and tie it;

• puts the balloon in the box.

Lesson phases

Introduction

1. The teacher assesses the level of students' knowledge. He asks them to discuss:

• substance construction;

• substances state of matter;

• arrangement of particles in various states of matter.

2. The teacher gives the subject and the purpose of the lesson in a language that the student understands as well as the criteria for success.

Realization

1. The teacher asks students to read the section of the abstract entitled „What is diffusion?” and in their own words, they define the concept of diffusion.

2. The teacher describes the activities necessary to conduct „Observation 1”, and then opens the balloon box. He asks students to present their observations and formulate conclusions.

3. The teacher displays a film presenting the phenomenon of diffusion. During the screening of the film, the students complete the form.

4. The teacher divides the students into groups. Each performs „Experiment 1” to investigate if the temperature affects the rate of diffusion. After completing the task, the groups compare their observations.

5. Students will read the section of the abstract entitled „The meaning of diffusion” and explain why diffusion is a very important or living organisms.

6. Students independently perform an interactive exercise.

Summary

1. The teacher asks pupils to assess the level of their knowledge gained during the lesson using the technique of traffic lights. Students raise the colored sheets of their flip‑boards

• green means that students understand everything;

• yellow is a sign that they have some doubts, so they should read the selected sections of the abstract once again;

• red means that the students have not understood most of the information discussed in the lesson and must therefore read the whole of the abstract.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Diffusion

Air fresheners, potpourri and incense are ways to give the room a pleasant fragrance. This is possible due to something we call diffusion. It is a process of the spreading and mixing of particles of various substances as a result of the movement of their particles. Conduct an experiment to understand exactly what diffusion is.

Diffusion in gases occurs quickly, because between the particles of each gas there is a lot of space that can be filled by particles of another substance. For example, when we remove a hot cake from an oven, we can smell its aroma almost immediately. Tiny particles come out of the cake which mix with air and reach our noses.
Diffusion also occurs in liquids whose particles also make quick movements. It can be easily observed in the home, e.g. when adding fruit syrup to water. In solids, the diffusion process takes place very slowly.

In solids, the movement of particles consists of vibrations around fixed positions. As the temperature rises, the particles begin to move faster. When a substance reaches its melting point, it’s physical state changes to liquid. The particles can then move (move away and closer together). For this reason, liquids – in contrast to solids – change shape (taking the shape of the container into which they were poured). However, in gases, the particles are far away from each other, move quickly and can move around freely. Since the temperature affects the speed of particle motion, can it also affect the rate of dissolution of the substance and diffusion?

Diffusion is of great importance in nature. Thanks to it, we can breathe, because oxygen from the air diffuses into the blood in our lungs. It also has many other uses in human life. Thanks to it, it is possible to build many devices and make them work.

• Diffusion is the spontaneous mixing of various substances due to the movement of particles.

• Liquids, solids and gases are made of particles that are constantly in motion. We can tell this by observing the changes of the substances state of matter and diffusion.

• The diffusion rate depends, among other things, on the temperature, mixing and particle size of the solute.