Topic: Exchange reactions

Target group

Elementary school student (grades 7. and 8.)

Core curriculum:

Elementary school. Chemistry.

III. Chemical reactions. 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 explains the essence of the exchange reaction.

Key competences

• communication in the mother tongue;

• communication in foreign languages;

• digital competence;

• learning to learn;

• mathematical competence and basic competences in science and technology.

Criteria for success
The student will learn:

• to explain what the exchange reaction is about;

• to save the equations of the exchange reaction along with the selection of coefficients, indication of substrates and products;

• to present the course of analysis reactions on models;

• to recognize exchange reactions based on their equations;

• to read and write the course of a chemical reaction in words;

• to describe a chemical experiment, including glass and laboratory equipment, chemicals, schema, observations and conclusions.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• exposing

  • film;

  • exposition.

• programmed

  • with computer.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• interactive whiteboard, tablets/computers;

• computers with internet access, or tablets;

• sets for building particle models.

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. Students will get acquainted with the content of the fragment „What are exchange reactions?” Together with the teacher, they analyze the equations of reactions and define the notion of replacement exchange.

2. The teacher announces a movie entitled „Reaction of lead(II) oxide with carbon”. Instructs students to write a research question and hypothesis in the form provided in the abstract. Then it displays the video and the students record their observations and conclusions. The teacher encourages young people to discuss, referring to the conclusions presented earlier.

3. The teacher conducts - in the form of a show - an experiment, according to the instructions in the abstract („Reaction of iron with copper(II) 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. The teacher asks a willing student to write on the board the equation of reaction that took place during the experiment (if the lack of volunteers, determines the student who will write the equation on the board), and then explains its mechanism.

4. The teacher divides the class into groups, distributes plasticine models and asks for the equation of the reaction that occurred during the show. Controls the course of work, gives advice and checks the correctness of the task.

5. Students will get acquainted with the fragment „Which chemical changes can be called exchange reactions?” And perform an interactive exercise. The teacher makes sure that the task has been correctly completed and gives feedback.

6. Work of the whole class team. Students stand in a circle. The teacher encourages them to play: throws a ball or mascot to one of the students, saying the English word or notion learned in the lesson. The student gives the Polish equivalent, mentions another word in English and throws a ball or mascot to a friend or colleague.

Summary

1. The students, working in pairs, create an infographic showing the issue learned during the lesson.

2. The teacher asks a willing student to summarize the lesson from his point of view. He asks other students if they would like to add anything to their colleague's statements.

Homework

1. Listen to the abstract recording to repeat the material and consolidate the new vocabulary.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Exchange reactions

Look at the following reaction equations.

As a result of each of these transformations two other products are created from two different substances.

The reactions presented follow the scheme:

${\text{substance}}_{\text{1}}\text{+}{\text{substance}}_{\text{2}}\text{→}{\text{product}}_{\text{1}}\text{+}{\text{product}}_{\text{2}}$

These reactions are said to be exchange reactions.

In this issue, examples of exchange reactions will be presented, as a result of which two other products are formed from two different substrates.

${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}\text{+ 2Al → 2Fe +}{\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}$

$\text{iron(III) oxide + aluminum → iron + aluminum oxide}$

This reaction proceeds according to the scheme:

${\text{substance}}_{\text{1}}\text{+}{\text{substance}}_{\text{2}}\text{→}{\text{product}}_{\text{1}}\text{+}{\text{product}}_{\text{2}}$

${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}\text{+ 3CO → 2Fe + 3}{\text{CO}}_{\text{2}}$

$\text{iron(III) oxide + carbon monoxide → iron + carbon dioxide}$

This reaction can be represented in the form of a schematic:

${\text{substance}}_{\text{1}}\text{+}{\text{substance}}_{\text{2}}\text{→}{\text{product}}_{\text{1}}\text{+}{\text{product}}_{\text{2}}$

• 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:
  ${\text{substance}}_{\text{1}}\text{+}{\text{substance}}_{\text{2}}\text{→}{\text{product}}_{\text{1}}\text{+}{\text{product}}_{\text{2}}$.