Topic: Fats – important changes

Target group

Elementary school student (grades 7. and 8.)

Core curriculum:

Primary school. Chemistry.

X. Chemical substances of biological importance. Pupil:

3 ) describes the structure of a fat molecule as an ester of glycerol and fatty acids; classifies fats in terms of origin, physical state and chemical nature; describes selected physical properties of fats; designs and conducts experiments to distinguish between unsaturated fat and saturated fat.

General aim of education

The student explains the transformations of fats

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to classify fats in terms of origin, physical state and chemical nature;

• what are the structure and properties of fats;

• to write down the fat hydrolysis reaction equation that takes place in the bodies of humans and animals;

• how to receive margarine on the example of oleic acid and write down the fat‑hardening reaction equation.

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 introduces students to the problem of hydrolysis of fats in human and animal organisms. In order to repeat and fix the material, he asks what hydrolysis is (what a process it is). Then, he refers students to the abstract and asks for an illustration of the illustration of the fat hydrolysis scheme. After a while, he writes an equation on the board and at the same time explains the mechanism of hydrolysis reaction of glycerol tripalmitate. He asks a willing student to write on the board the equation for the hydrolysis reaction of glyceryl trioleate..

2. The lecturer asks students to look at the illustration of the course of fat‑curing reactions in the abstract. He writes down the equation on the board again, explaining the mechanism of the hydrogenation reaction of unsaturated fats..

3. The teacher recommends students to watch the film „How to distinguish vegetable oil from mineral oil”. Earlier, the students write down the research question and the hypothesis in the form in the abstract, and after the projection - observations and conclusions. Selected people present the results of their work. The teacher, referring to them, encourages young people to discuss.

4. The teacher asks students to do interactive exercises in the abstract. Volunteers discuss correct solutions, the teacher corrects possible mistakes, explains all doubts.

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

Fats – important changes

What changes do fats undergo in human and animal bodies?

Fats undergo hydrolysis, i.e., they decompose forming glycerol and fatty acid. This process takes place in the digestive tract under the influence of enzymes, and is an energy source. The following is a simplified scheme for these processes.

How is margarine made?

Liquid fats are subjected to a process of industrial hardening which results in margarine. This process consists in catalytic hydrogenation of unsaturated fats. The result is saturated compounds – solid fats.

Is it possible to obtain soap from fats?

An important process undergone by fats is their saponification. This reaction involves heating of fats in the presence of sodium or potassium hydroxide. The product of this reaction is sodium and potassium salts of higher carboxylic acids, i.e., soaps.

Are all fatty substances fats? Are vegetable oil and diesel oil fats?

When vegetable oil is heated intensely, a substance with a suffocating odour is released. This substance is acrolein. It causes severe irritation of mucous membranes, eyes and upper airways. It is toxic and carcinogenic, which is why fats should not be overheated. This is an identification reaction for fats (the so‑called acrolein test). Identification reaction is a reaction that allows to identify a particular compound or group of compounds. Mineral oils do not form such a product when heated.

• Fats are esters of glycerol and higher carboxylic acids.

• Fats can be divided – by their state of aggregation – into solid and liquid ones.

• Fats are divided according to their origin into vegetable and animal fats.

• Vegetable fats contain mainly unsaturated compounds, whereas animal fats – saturated compounds.