Topic: Solubility of substances - tasks

Target group

Elementary school student (grades 7. and 8.)

Core curriculum

Elementary school. Chemistry.

V. Water and aqueous solutions. Pupil:

6) reads the solubility of substances from the solubility table or from the solubility plot; calculates the mass of the substance that can be dissolved in a given amount of water at the given temperature;
7) performs calculations using the following notions: solubility, percent concentration (mass percentage), mass of substance, solvent mass, mass of solution, solution density (using solubility table or solubility plot.

General aim of education

The student solves the tasks taking into account the solubility of the substance

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 interpret solubility curves to determine the solubility of a substance or type of solution (saturated, unsaturated);

• to calculate the mass of substance needed to make its solution saturated at a specific temperature;

• to calculate the mass of the components (solute and solvent) of the saturated solution at the set temperature.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• 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;

• projector;

• interactive whiteboard, tablets/computers;

• 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. Teacher – in order to remind the news from the last lesson – he asks questions, for example, what is the solubility, what determines the solubility, how can be obtained from saturated solution unsaturated solution, how saturated solution can be obtained from an unsaturated solution – willng students answer.

2. The teacher refers students to the abstract and paragraph „Reading and interpreting the data from the solubility plot” and discusses computational problems that can be solved using solubility and solubility curves. To train students' skills:

   • calculating the mass of a given substance needed to make its saturated solution that can be dissolved at a specific temperature,

   • calculating the mass of the components (solute and solvent) of the saturated solution at the set temperature and calculating the mass ratio of solute and solvent in the saturated solution at the specified temperature,

   the teacher displays exercises 1–4 on the multimedia board. He divides the class into groups and assigns each exercise. Representatives of groups present solutions, and the teacher watches over their correctness.

3. The teacher asks students how to use a solubility curve to find how to obtain a saturated solution at a given temperature. Students look for information in available sources (e‑textbook, internet, etc.). Then, willing/selected students answer: From the curve, we read how many grams of substance should be dissolved in 100 g of water. By making further calculations, we get information about the mass of the substance that can be dissolved in any mass of water. Then students in pairs solve exercises 5 and 6 – they calculate the amount of substance that can be dissolved in a certain amount of water at a given temperature.

4. The teacher asks students: How to inform students how to calculate the amount of substance present in any mass of saturated solution? Students present their suggestions during a brainstorming session. Then, along with the teacher, they verify it. Students in pairs solve exercises 7–9 – they calculate the amount of substance present in any mass of saturated solution.

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

Solubility of substances - tasks

Based on the solubility plot, we can determine how many grams of the substance will dissolve in 100 g of water and create a saturated solution at a given temperature. We can also predict whether the given mass of substance can dissolve in a given mass of water.

From the graph solubility curve we can read how many grams of substance should be dissolved in 100 g of water to obtain a solution saturated at a certain temperature. By making further calculations, we get information about the mass of the substance that can be dissolved in any mass of water.

Knowing the solubility of a substance in water, we can easily determine the mass ratios between a solute and a solvent in a saturated solution. This in turn allows us to calculate the amount of substance present in any mass of saturated solution.

• Based on the knowledge of the solubility of a substance, you can: determine the amount of substance that will dissolve in 100 g of water and any mass of water, creating a saturated solution at a given temperature, assess whether the given amount of substance can dissolve in a given mass of water.