Topic: Exchange reactions - single and double exchange

Target group

Elementary school student (grades 7. and 8.)

Core curriculum

Elementary school. Chemistry.

III. Chemical reactions. The student:

2) gives examples of different types of reactions (synthesis reaction, analysis reaction, exchange reaction); indicates substrates and products.

General aim of education

The student writes the equations of the exchange reaction.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to explain what the exchange reactions are;

• to recognise exchange reactions based on their equations;

• to describe chemical experiments, including: glass and laboratory equipment, chemical reagents, apparatus design;

• to formulate observations and conclusions from experience;

• to obey OHS rules when performing chemical experiments.

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.

Realization

1. The teacher introduces the students to the issue implemented during the lesson. He announces a movie titled „Reaction of copper(II) oxide with carbon”. 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.

2. In the abstract, the students search for information about the reduction‑oxidation reactions and explain in their own words what this type of reaction is. Next, they discuss a table containing examples of exchange reactions during which oxides are reduced.

3. The teacher asks students to read the fragment titled „Single and double exchange reactions” and try to remember its content. Then the participants, working in pairs, ask each other about the knowledge of the fragment.

4. The teacher brings the content of the movie titled „Reaction of silver nitrate with potassium chloride”. 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. Selected people present the results of their work.

5. The teacher plays the abstract recording for all students. Participants listen carefully and give feedback on the difficulty of the text being heard using the traffic light method. Students are provided with green, yellow and red cards. While listening to the recording, they display the appropriate color for self‑assessment and to inform the teacher: green - I'm fine, I understand everything; yellow - I have some doubts; red - I do not understand anything, please help. The teacher responds depending on the needs of the students, deciding to repeat the recording, listen to the recording while following the text or translate the text.

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. The teacher briefly presents the most important issues discussed in class. He answers the additional questions of the proteges and explains all their doubts.

2. The teacher asks the students questions:

   • What did you find important and interesting in class?

   • What was easy and what was difficult?

   • How can you use the knowledge and skills you have gained today?

   Willing/selected students summarize the lesson.

Homework

1. Carry out task number nr 3.1.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Exchange reactions - single and double exchange

The reaction of combining the substance with oxygen as well as the transformation in which the oxide undergoes „deoxidation” are examples of as an example of reduction‑oxidation (redox) reaction. All the reactions learned in this module, as a result of which metal was formed from the metal oxide, are examples of redox reactions. The metal oxide is reduced to the metal and substance that receives oxygen from a metal oxide becomes oxidised. That substance is called reducing agent or reductant.

In metallurgy, coal is often used to reduce metal oxides. Its sources are relatively cheap and easily accessible. However, it can only reduce some metal oxides. These include, for example, oxides of: zinc, iron, lead, copper. These oxides, heated with carbon, are reduced to free elements, while the carbon is oxidized. However, many metal oxides can not be reduced with carbon. Other methods are used to obtain pure elements.

It stands out among the exchange reactions single exchange reactions and double‑exchange reactions. The first type, a single exchange reaction, is a transformation in which two substrates (element and chemical compound) are transformed into two products (new simple and complex substance). Its course can be described by the following scheme:

${{\text{compound}}_{\text{1}}\text{+ element}}_{\text{1}}\text{→}{\text{element}}_{\text{2}}{\text{+ compound}}_{\text{2}}$

The second group are the double exchange reactions. They occur when two complex substances are transformed into two new chemical compounds. The diagram below illustrates the course of a double exchange reaction:${\text{compound}}_{\text{1}}\text{+}{\text{compound}}_{\text{2}}\text{→}{\text{compound}}_{\text{3}}\text{+}{\text{compound}}_{\text{4}}$

• In addition to the analysis and synthesis reaction, there is a third type of reaction – exchange reaction.

• The exchange reaction is a transformation during which the components exchange between the reacting substances takes place. It runs according to the scheme:
  ${\text{substance}}_{\text{1}}\text{+}{\text{substance}}_{\text{2}}\text{→}{\text{product}}_{\text{1}}\text{+}{\text{product}}_{\text{2}}$.

• The exchange reactions can be divided into two groups: single exchange reactions and double exchange reactions.

• The single exchange reaction is a transformation, during which two substrates (element and chemical compound) are transformed into two products (new simple and complex substance).

• The double exchange reaction is a transformation, during which two compound substances are transformed into two chemical compounds.

• The reduction‑oxidation (redox) reaction is an example of an exchange reaction.