Topic: Hydracids

Target group

Elementary school student (grades 7. and 8.)

Core curriculum:

Szkoła podstawowa. Chemia.  

VI. Hydroxides and acids. Student:

1) recognizes formulas of hydroxides and acids; writes the summary formulas of hydroxides: NaOH, KOH, Ca(OH)Indeks dolny 2₂, Al(OH)Indeks dolny 3₃, Cu(OH)Indeks dolny 2₂ and acids: HCl, HIndeks dolny 2₂S, HNOIndeks dolny 3₃, HIndeks dolny 2₂SOIndeks dolny 3₃, HIndeks dolny 2₂SOIndeks dolny 4₄, HIndeks dolny 2₂COIndeks dolny 3₃, HIndeks dolny 3₃POIndeks dolny 4₄ and give their names;

2) designs and carries out experiments that can give you a hydroxide (soluble and sparingly soluble in water), hydracids and oxoacids (e.g., NaOH,Ca(OH)Indeks dolny 2₂, Cu(OH)Indeks dolny 2₂, HCl, HIndeks dolny 3₃POIndeks dolny 4₄); writes down the corresponding reaction equations in the molecular form;

3) describes the properties and resulting applications of certain hydroxides and acids (e.g., NaOH, Ca(OH)Indeks dolny 2₂, HCl, HIndeks dolny 2₂SOIndeks dolny 4₄).

General aim of education

The student discusses the structure, preparation, properties and use of hydracids

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 define the concept of acid;

• to design experiments to obtain hydracids by various methods;

• to describe the structure of hydracids ;

• to determine the color that the indicators in acids take;

• to investigate and describe the properties and use of selected hydracids .

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;

• projector;

• interactive whiteboard, tablets/computers;

• methodician or green, yellow and red cards;

• equipment, laboratory glass and reagents for the experiment - see description of experience 2 in the e‑textbook and instructions in the methodical commentary;

• stiletto‑ball models;

• sheets of paper, markers.

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 issue of hydracids, asks questions in relation to the knowledge gained in biology lessons, eg. What acid is found in the stomach of a human being? What is its role? - targeted discussion.

2. The teacher conducts a teachers' show according to the experience 2 instructions in the abstract. The students observe the changes taking place and start the discussion. The teacher asks the question: „Why did methyl orange turn red during the experiment, what does it show?”. Then he writes on the board the equation of reaction that took place during the experiment - the students copy them to the notebooks. After a while, they receive a rod‑ball model and build a model of a hydrochloric acid molecule. The teacher asks them to present a mechanism for the reaction of obtaining hydrochloric acid on these models.

3. The teacher writes on the board, at the same time explaining the equation for the reaction of hydrosulfuric acid production - the students write them to the notebooks. Next, they build a model of a hydrosulfuric acid molecule and present with it a mechanism for the reaction of obtaining this acid.

4. Teacher and pupils together construct, in reference to hydrochloric and hydrosulfuric acid, the general formula of hydracids - eagerly writes it on the blackboard.

5. The teacher displays a table with examples of hydracids from the abstract - together with the students they analyze it.

6. The teacher instructs students to prepare an observation journal in abstract (or work sheets) and informs them that they will watch the film „Testing the properties of hydrochloric acid”. After the issue of the material, they discuss the observations and then determine and record the conclusions in the indicated place. The teacher discusses the properties of hydrosulfuric acid.

7. The teacher divides the students into groups and refers to the abstract, the e‑textbook and other sources to prepare posters on the use of hydrochloric acid. After completing the work, group leaders using the technique of a talking wall report the effects of activities.

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

Hydracids

Under the influence of some chemical compounds, the pH indicators change colour in a way that is easy to observe. The indicator is, for example, the tea brew. After adding hydrochloric acid solution to it, its colour changes to yellowish. Let's check if similar properties are shown by red cabbage brew, phenolphthalein and methyl orange.

Hydracids are obtained, inter alia, by dissolving in water the chemical compound formed during the reaction of hydrogen with some non‑metals, e.g.

HIndeks dolny 2₂ + ClIndeks dolny 2₂ → 2HClIndeks dolny (g)_(g)

${\mathrm{HCl}}_{\left(\mathrm{g}\right)}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to }{\mathrm{HCl}}_{\left(\mathrm{aq}\right)}$

where:
$\text{g}$ – means that substance is a gas,
$\text{aq}$ – means that substance is an aqueous solution.

Hydrogen sulphide can be obtained by hydrogen and sulphur synthesis as following:

HIndeks dolny 2₂ + S → HIndeks dolny 2₂SIndeks dolny (g)_(g)

${\mathrm{H}}_2{\mathrm{S}}_{\left(\mathrm{g}\right)}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to }{\mathrm{H}}_2{\mathrm{S}}_{\left(\mathrm{aq}\right)}$

Hydracids form also other chemical elements of the 17th group of the periodic table: fluorine, bromine and iodine. In the name of hydracids you add ending ic instead of ine (exception: sulphur) to the name of the non‑metal and add prefix hydro in front of it.
– hydrobromic acid
– hydrochloric acid
– hydroiodic acid

General formula of acid is:

where:
$\text{n}$ – number of atoms in the acid molecule,
$\text{R}$ – acid residue (for hydracid these are non‑metal atoms).

Acids are chemical compounds whose molecules are made of hydrogen atoms and an acid residue. In molecules of hydracids, hydrogen atoms bond directly to the non‑metal atom.

Hydrogen chloride it is a colourless gas with a sharp, choking smell. It dissolves very well in water. The aqueous solution of hydrogen chloride is called hydrochloric acid or muriatic acid.

Hydrogen chloride is used as a chemical reagent in the process of metalworking, for the production of plastics, sugar, artificial honey, spices, homogenized cheese and curd. Hydrogen sulphide is used as a chemical reagent to detect ions of some metals.

• There are no oxygen atoms in molecules of hydracids, and hydrogen atoms are bonded directly with the atoms of non‑metal.

• These are formed as a result of dissolution in the water of the product of hydrogen synthesis with non‑metal.

• Hydrogen chloride and hydrogen sulphide are poisonous gases. Their aqueous solutions are acidic.