Topic: Separation of homogeneous mixtures

Target group

Elementary school student (grades 7. and 8.)

Core curriculum:

Elementary school. Chemistry.

I. Substances and their properties. Student:

5) describes the characteristics of homogeneous and heterogeneous mixtures;

6) prepares mixtures and selects the method of separation of mixture components (e.g. filtration, distillation, separation of liquid in a separator); indicates these differences between the physical properties of the constituents of the mixture that enable its separation;

7) describes the differences between the mixture and the chemical compound or element;

General aim of education

The student uses different methods of separating homogeneous mixtures.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• plan and carry out separation of homogeneous mixtures into components (eg water and rock salt, ethanol and ink, potassium nitrate and water).

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 instructs students to follow the command No. 1 and exercise No. 1.

2. The teacher asks students to read the fragment „How do you separate the mixtures?” and try to remember its content. Then the participants working in pairs, ask each other about the knowledge of the fragment.

3. The teacher asks the students what method they would choose for the separation of the mixture of sodium chloride and water - there is a brief discussion. After that, the lecturer instructs students to prepare an observation log in the abstract. They are to write the research question and the hypothesis, followed by the observations and conclusions from the film „Separation of the mixture of sodium and water chloride”, which they will see at a glance. After the screening, the teacher asks the students about the property of the of the mixture, which was used to separate it into components - the discussion continues..

4. The teacher refers the participants to the abstract and asks to familiarize with instructions of experiments „Preparing and separating a mixture of water and water” and „Preparing and separating a mixture of water and potassium nitrate”. He or she divides students into groups, distributes work cards and appropriate equipment, glass and reagents to perform the experiment. Students - with the help of a teacher - formulate hypotheses and write them in the form in an abstract. Then they follow the instructions. They record the observations in the form. The teacher asks questions in relation to the observations recorded. He or she initiates the discussion, the conclusions of which students write on the form.

5. 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.

6. Expanding and enriching English vocabulary in the issues covered in the lesson - students perform language exercises included in the abstract. The teacher makes sure that the tasks have been correctly completed and gives feedback.

Summary

1. The teacher asks the students to finish the following sentences:

   • Today I learned ...

   • I understood that …

   • It surprised me …

   • I found out ...

   The teacher can use the interactive whiteboard in the abstract or instruct students to work with it

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.

2. 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

Separation of homogeneous mixtures

Homogeneous mixtures can be separated by:

• evaporation – 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 – a method of separating multi‑component liquid mixtures that differ in boiling point; it involves moving into steam and then condensing it;

• chromatography – a method for separating or testing the composition of mixtures of chemical compounds; uses the differences in the speed of movement of the components of the mixture - e.g. different dyes on the strip of tissue immersed in the liquid (vinegar, spirit, acetone);

• 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 for separating homogeneous mixtures include: solvent evaporation (eg water), distillation, crystallization, chromatography.

• The methods of separation of inhomogeneous mixtures include: sedimentation, decanting, filtration, mechanical separation, separation by means of a separator.

• Some techniques should be used when separating some mixtures. When separating the mixture of rock salt and chalk, we should successively: dissolve the mixture in water (rock salt will dissolve), filter (chalk will remain on the filter), evaporate the filtrate (rock salt will remain).