Topic: Synthesis reactions - principles

Target group

Elementary school student (grades 7. and 8.)

Core curriculum:

Elementary school. Chemistry.

III. Chemical reactions. Pupil:

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

General aim of education

The student writes down the synthesis reaction equations

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.

Criteria for success
The student will learn:

• to describe what the synthesis reactions are based on;

• to indicate examples of synthesis reactions;

• to write the synthesis reaction equations.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• 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;

• sets for building particle models;

• methodician or green, yellow and red cards.

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 conducts - in the form of a show - an experiment, according to the instructions in the abstract (Experiment 1: “Study of the reaction of magnesium with oxygen”). 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. .

2. The teacher discusses the course of chemical transformation (reaction of magnesium with atmospheric oxygen), including substrates and products. Next, he writes an equation of the chemical reaction on the board using the names of the elements and the chemical compound and the same equation using the symbols of elements and the formula of the chemical compound. He explains the rules that apply when writing equations of chemical reactions.

3. The teacher divides the class into groups, distributes sets for building particle models and asks for the equation of the reaction that takes place during the show. He monitors student's work, gives advice and checks the correctness of the task, The teacher points the person who shares his insights and explains the reasonableness of the conclusions noted.

4. Students read the fragment titled „How do we call the reaction, as a result of which substances combine with each other to form one chemical compound?” and define the synthesis reaction. The teacher explains what the analysis reaction is.

5. The teacher announces a movie titled “Study of the reaction of iron with sulfur”. He instructs his pupils 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 points the person who shares his insights and explains the reasonableness of the conclusions noted. Referring to observations and conclusions, the teacher encourages young people to discuss.

6. An eager student discusses the course of chemical transformation (reaction of iron with sulfur), including substrates and products. Next, he presents the equation of chemical reaction on the board with the names of elements and chemical compound and with symbols of elements and the formula of the chemical compound.

7. Students, working in groups, re‑use sets for building particle models - they form the equation of reaction presented in the film.

8. 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. Teacher asks: If there was going to be a test on the material we have covered today, what questions do you think would you have to answer? If the students do not manage to name all the most important questions, the teacher may complement their suggestions.

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. 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

Synthesis reactions - principles

The course of chemical transformation, including substrates and products, can be described in words, for example: carbon reacts with oxygen and as a result of this reaction carbon dioxide is formed. Instead of a long description, one can use a reaction equation containing names of elements and chemical compounds:

$\text{carbon + oxygen → carbon dioxide}$

Although the above methods of presenting the course of chemical reactions are correct, it turns out to be of little use to chemists. In their work, they use equations of reactions in which they use symbols of elements and chemical formula. The chemical transformation discussed above is recorded using the following reaction equation:

${\text{C +O}}_{\text{2}}{\text{→ CO}}_{\text{2}}$

In order for the equation to be correctly written, the number of atoms of particular elements recorded on both sides of this equation must be identical. In the reaction equation presented above (${\text{C +O}}_{\text{2}}{\text{→ CO}}_{\text{2}}$) obtaining carbon dioxide from carbon and oxygen this condition is met.

The number of atoms of each element on both sides of the equation is the same. The reaction equation is written correctly. It is said that it is agreed or balanced. The activities that we have been doing since writing the equation of reactions using symbols and formulas to obtain its correct recording are called reconciliation (or balancing) of the reaction equation.

Look at the following reaction equations:

$\text{hydrogen + oxygen → water}$

${\text{2H}}_{\text{2}}{\text{+O}}_{\text{2}}{\text{→2H}}_{\text{2}}\text{O}$

$\text{carbon + oxygen → carbon dioxide}$

${\text{C +O}}_{\text{2}}{\text{→ CO}}_{\text{2}}$

$\text{hydrogen + chlorine →hydrogen chloride}$

${\text{H}}_{\text{2}}{\text{+Cl}}_{\text{2}}\text{→ 2HCl}$

Note that as a result of these transformations, one product is obtained from two elements. They can be described by the following equation:

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

Such conversions are said to be synthesis reactions or otherwise linking reactions.

• Equations of chemical reactions are recorded using symbols and chemical formulas. The number of atoms of individual chemical elements on both sides of the equation must be identical.

• Supplementing the equation of the reaction with stoichiometric coefficients is called reconciliation (balancing) the chemical reaction equation.