Topic: How can you separate the mixtures found in everyday life?

Target group

Elementary school student (grades 7. and 8.)

Core curriculum:

Primary school. Chemistry.

I. Substances and their properties. Pupil:

6) prepare mixtures and selects the method of separation of mixture components (eg filtration, distillation, separation of liquid in a separator); indicates these differences between the physical properties of the mixture components that enable it to be separated.

General aim of education

The student mentions different ways of separating mixtures with the indication of differences in the physical properties of the mixture components used in these methods.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to list and characterize the methods for separating mixtures;

• to indicate differences between the physical properties of the mixture components that enable their separation.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• exposing

  • film.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• 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, introducing students to the subject of mixture separation, states that if substances are mixable, the components of the resulting mixtures can also be separated. Methods for separating mixtures are based on the use of differences in the physical properties of their components, e.g. solubility in water, boiling point, melting point, sorption properties, interaction with a magnet or density.

2. The teacher presents methods of separating mixtures and briefly characterizes them. He asks students to indicate examples of mixtures for each distribution method. Among the methods of separating mixtures into components indicates: mechanical methods (eg the use of riddles (sieves), pensits, magnets) displays the film „Separating the mixture of sulfur and iron” on the multimedia board Students observe changes and record conclusions and observations in the observation diaries in abstract ), sedimentation, decantation, filtration, sorption (using activated carbon in filters for drinking water purification), separator, evaporation, crystallization, distillation, chromatography, extraction, whipping (creation of butter), centrifugation, rectification.

3. The lecturer displays on the multimedia board the drawings „Separation of mixtures in practice” - students analyze them in terms of using the physical properties of ingredients to separate the mixture; eager to discuss drawings.

4. At the end of the lesson, the teacher asks students to do interactive exercises in the abstract.

Summary

1. The student indicated by the teacher sums up the lesson, telling what he has learned and what skills he/she has been practicing.

Homework

1. Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

How can you separate the mixtures found in everyday life?

In order to plan the method of separating the mixture, the analysis of the properties of its components should be performed and differences should be used. Mechanical methods (mechanical separation) allow to separate components forming a heterogeneous mixture. These methods use the differences:

• appearance (e.g. manual sorting, using a tweezers or sieve – salt and pepper);

• magnetic properties (using magnet – sulphur and iron);

• differences in solubility (e.g. in water – chalk and salt, water, oil).

Heterogenous mixtures can be separated using following methods:

• filtration (seeping) – solids are retained on the sieve, drain or filter; this process can be observed by straining pasta on a sieve;

• sedimentation– gravitating of solid substances to the bottom under the influence of gravity; it is used in sewage treatment plants;

• decantation – pouring off the liquid, leaving the sediment behind; it can be observed during draining off potatoes after being boiled or poring off the tea or coffee and leaving the leaves or coffee grounds behind;

Homogenous mixtures can be separated using following methods:

• vaporization – heating up the liquid mixture and the solid dissolved in it to evaporate the liquid; this process is used in the preparation of jam, while in countries with a warm climate it is the effect of evaporation of sea water and the formation of rock salt deposits;

• crystallization – this technique allows the separation of solid crystals from the solution;

• distillation.

The heterogeneous mixture can be separated due to the fact that its components have different magnetic properties.

• The mixtures can be separated using various techniques.

• Separation methods depend on the type of mixture and use the properties of its components.

• The methods of separating homogeneous mixtures include: solvent evaporation (e.g. water), distillation, crystallization, chromatography.

• The methods of separating heterogeneous mixtures include: sedimentation, decantation, filtration, mechanical separation, separatory funnel separation.