Qualitative composition of sulfuric acid. Carrying out reactions confirming the qualitative composition of inorganic substances. Sequence of work

Lesson - Practical work number 4 (grade 9)

Lesson type: lesson- practiceusing information and communication technologies.

Topic: Solution experimental tasks on the topic: "Oxygen subgroup".

Lesson Objectives:

I ... formation of UUD

1. Personal UUD - the possibility of self-determination in practical work on intellectual capabilities (the organizer takes a sheet, evaluating his abilities and capabilities).

2. Regulatory UUD - goal formation, planning and organization of activities, forecasting, control, correction, assessment.

3. Cognitive UUD - research actions (application of knowledge in a specific situation, solving experimental problems, as a component of the education of logical thinking)

4 Communicative UUD - organization and planning of work in a group, the ability to negotiate and find a common solution, building interpersonal relationships.

II. Using knowledge about qualitative reactions to ions, empirically learn to recognize chemical substances;

III. Develop the cognitive activity of students in the process of performing the experiment;

IV. To bring up accuracy, respect for the expenditure of chemical reagents;

V. To consolidate the skills of working with the virtual laboratory.

During the classes

Organizational moment.

Hello guys. Today we have guests at the lesson, these are the chemistry teachers of the schools of our region. Turn around, greet them. Amazing. Have a seat. I hope everyone has prepared notebooks, pens, pencils for the lesson. Then let's get started.

Motivation :: add a word to a phrase

CHEMICAL

Pay attention to the board. I wrote only one word "CHEMICAL", add words to get phrases (EXPERIMENTS, REACTIONS, PHENOMENA, PROCESSES, etc.)

Tell me, is there anything that can unite all these phrases? (Practical work).

Right. And today in the lesson we will do practical work with you. We work, as usual, in groups. Open notebooks, write down the number and topic of the work "Solving experimental problems on the topic" Oxygen subgroup ".

At home, you prepared for today's lesson, looked at the problems on pages 146-147 of your textbooks, and thought about your goal. How do you think it should sound?

to apply the knowledge gained during the study of the topic "Oxygen subgroup" in the experimental solution of problems;

to consolidate the skills of conducting a chemical experiment.

Okay, let's write down the purpose of the work in a notebook.

Do you need to work successfully and without health consequences?

Comply with the safety rules and rules for working in groups.

We repeat the rules of T.B. (we repeat according to the table, where only pictures are left)

RULES FOR WORK IN GROUPS:

Compliance with all safety rules

Observe silence, do not disturb others, they work too

Speak your thoughts, do not criticize others

Know how to negotiate, find a common solution.

On the tables there is a folder with instructions for performing the work. (20 minutes)

Distributing roles

A) organizer (works with an instruction card, figuring out what to do, gives instructions to the performer)

B) performer - practitioner (conducts reactions)

C) controller-analyst (analyzes observations and corrects the work of the organizer)

We will solve the first problem (problem no. 4 on page 147) with the help of a virtual laboratory. I invite one person from each group. Guys, quickly assign roles. Have you decided? Getting started. I remind the guys in the groups about drawing up a reporting table.

Thanks. You can sit down and continue to work in your groups, but in different roles.

Conclusion : What conclusion did you make based on the results of your work? Let's correct it.

Guys, our lesson is coming to an end. What can you say about today's work?

- I succeeded most of all ……

- I can praise myself for ...

- I can praise my classmates ... ..

- I was surprised ... ...

- In my opinion, it was not possible ... .. because …….

-For the future I will take into account ……….

Okay, now

Everyone takes trays and notebooks to the teacher's demonstration table, tidies up the workplace

Final part.

Thank you all for your work,you will learn the results in the next lesson. At home, repeat the composition of the air and think about the next task.

HOME EXPERIENCE

From the proposed materials: 50ml., 9% acetic acid, 1 tablespoonNaHCO 3 (c ode), 100ml. H 2 O, 1 st. a spoonful of detergent, beet juice, salted dough or plasticine. offer instructions for conducting a chemical experiment that can serve as a visual aid in a geography lesson in grade 6

Practical work number 4
Experimental tasks on the topic "Oxygen subgroup"

Problem 1

Carry out reactions confirming the qualitative composition of sulfuric acid. Write down the reaction equations.

Problem 2

Place 1-2 zinc granules in a test tube and pour about 1 ml of diluted sulfuric acid into it. What are you seeing? Write the equation for the reaction and consider redox processes.

Problem 3

Pour 1-2 ml of sodium sulfide solution into two tubes. Pour the same volume of chlorine water into one of them, and bromine water into the other. What are you seeing? Explain your observations. Write the equations of the corresponding reactions in molecular and ionic form.

Problem 4

You are given three test tubes of solutions. Determine which one contains hydrochloric acid, sulfuric acid and sodium hydroxide. Write the equations of the corresponding reactions in molecular and ionic form.

Problem 5

Determine if table salt contains sulfates. Write the reaction equations in molecular and ionic form.

Problem 6

With the help of characteristic reactions, determine whether the salt given to you is sulfate, iodide or chloride. Write the equations of the corresponding reactions in molecular and ionic form.

Problem 7

Starting from copper (II) oxide, get a solution of copper (II) sulfate and isolate crystalline copper sulfate from it. Write the equations of the corresponding reactions in molecular and ionic form.

Problem 8

You are given three tubes of sodium sulfate, sulfite, and sodium sulfide solutions. Determine with only one reagent in which tube each of the substances is located. Write the equations of the corresponding reactions in molecular and ionic form.

Practical work number 5
Experimental tasks on the topic "Subgroups of nitrogen and carbon"

Problem 1

Carry out reactions that can be used to prove that the substance given to you in closed vessels is:

a) ammonium chloride;
b) sodium carbonate;
c) ammonium nitrate;
d) ammonia;
e) calcium carbonate;
f) sodium silicate.

Problem 2

Prove empirically that ammonium sulfate and ammonium nitrate cannot be mixed with lime before applying these fertilizers to the soil, and explain why. Write down the reaction equations.

Problem 3

Prove empirically that:

Write the equations of the reactions carried out in molecular and ionic form.

Problem 4

Get ammonia from the following salts:

a) ammonium chloride;
b) ammonium sulfate;
c) ammonium nitrate.

Write the equations of the reactions carried out in molecular and ionic form.

Problem 5

Perform reactions that are expressed by abbreviated ionic equations:

Write the equations of the reactions carried out in molecular and ionic form.

In four test tubes you are given crystalline substances: sodium sulfate, zinc chloride, potassium carbonate, sodium silicate. Determine which tube contains each of the substances. Write the reaction equations in molecular and ionic form.

Practical work number 6
Receiving, collecting and recognizing gases

Option 1

Experience 1.
Receiving, collecting and recognizing hydrogen

Assemble the gas generating device and check for leaks. Put 1-2 zinc granules in a test tube and add 1-2 ml of hydrochloric acid to it. Close the tube with a stopper with a gas outlet tube (see Fig. 76) and place another tube on the tip of the tube. Wait a while for the tube to fill with evolved gas.

Remove the test tube from the gas outlet tube and, without turning it over, slightly tilting it, bring it up to the burning alcohol lamp with a hole. If there is pure hydrogen in the test tube, then a dull clap will be heard, if there is a "barking" sound, hydrogen is collected in a mixture with air, that is, "detonating gas" is collected in the test tube.

Questions and tasks:

1. What happens when zinc interacts with hydrochloric acid? Make up the equation of the reaction and give its characteristics for all the studied signs of the classification of chemical reactions.
2. Describe the physical properties of hydrogen directly observed during the experiment.
3. Describe how hydrogen can be recognized.

Experience 2.
Receiving, collecting and recognizing ammonia

Assemble the device as shown in Figure 168 and check it for leaks.

Rice. 168.
Ammonia production and collection by air displacement

Pour one spoonful of ammonium chloride and calcium hydroxide into a porcelain cup to burn the substances. Stir the mixture with a glass rod and pour into a dry test tube. Close it with a stopper and fix it in the tripod leg (pay attention to the inclination of the test tube relative to the hole!). Place a dry ammonia collection tube on the flue gas tube.

First, heat the entire tube with a mixture of ammonium chloride and calcium hydroxide with 2-3 movements of the flame, and then heat only in the place where the mixture is located.

To detect ammonia, bring a damp phenolphthalein paper to the opening of an upside-down test tube.

Stop heating the mixture. Remove the test tube containing ammonia from the gas outlet tube. Immediately close the end of the flue gas pipe with a piece of wet cotton wool.

Immediately close the opening of the removed vial with your thumb, immerse the vial with the hole down in the vessel of water and empty the hole in the vial. What are you seeing? Why did the water rise in the test tube? Close the opening of the tube under water with your finger and remove it from the vessel. Invert the tube and add 2-3 drops of phenolphthalein solution to it. What are you watching?

Carry out a similar reaction between alkali and ammonium salt solutions when heated. Place a damp indicator paper over the opening of the tube. What are you watching?

Questions and tasks:

1. What happens when ammonium chloride and calcium hydroxide react? Make up the equation of the reaction and give its characteristics for all the studied signs of the classification of chemical reactions.
2. Describe the physical properties of ammonia directly observed in the experiment.
3. Describe at least two ways to recognize ammonia.

Option 2

Experience 1.
Receiving, collecting and recognizing oxygen

Assemble the device as shown in Figure 109 and check for leaks. Fill the test tube about 1/4 of its volume with potassium permanganate KMnO 4, place a loose ball of cotton wool at the tube opening. Close the tube with a stopper with a gas outlet tube. Attach the tube to the leg of the tripod so that the end of the flue tube reaches almost to the bottom of the oxygen collection vessel.

First, heat the entire tube with KMnO 4 with 2-3 movements of the flame, and then heat only in the place where the substance is located.

Check the presence of oxygen in the vessel with a smoldering splinter.

Questions and tasks:

1. What happens when potassium permanganate is heated? Make up the equation of the reaction and give its characteristics for all the studied signs of the classification of chemical reactions.
2. Consider the recorded reaction in terms of redox processes.
3. Describe the physical properties of oxygen directly observed in the experiment.
4. Describe how you recognized oxygen.

Experience 2.
Receiving, collecting and recognizing carbon monoxide (IV)

Place a few pieces of chalk or marble in a test tube and add 1-2 ml of diluted hydrochloric acid. Close the tube quickly with a stopper with a vent tube. Dip the end of the tube into another tube with 2-3 ml of lime water.

Watch gas bubbles pass through the lime water for a few minutes.

Questions and tasks:

1. What happens when chalk or marble interacts with hydrochloric acid? Make up the equation of the reaction and give its characteristics for all the studied signs of the classification of chemical reactions.
2. Consider the reaction carried out in the light of the theory of electrolytic dissociation.
3. Describe the physical properties of carbon monoxide (IV) directly observed in the experiment.
4. Describe how you recognized carbon monoxide (IV).

Sections: Chemistry

Lesson form: practical work.

Lesson Objectives:

• Educational:

To repeat and consolidate practical skills and abilities in performing chemical experiments, handling reagents, observing safety rules;
- learn to select the reagents necessary for work, assume the observed phenomena, draw conclusions;
- to consolidate the skills of drawing up the equations of reactions of ion exchange, drawing up equations of dissociation, complete and abbreviated ionic equations.

• Developing:
continue the development of self-education skills - work with a methodological guide, additional literature.

• Educational:

To continue the formation of worldview concepts about the cognizability of nature, the causal relationship between the composition, structure and properties of substances;
- Pupils must be able to work accurately, consciously follow the established rules (for example, safety precautions).

Equipment: overhead projector with code films, solubility table, TV set, programmed methodological manual, tables for filling out the work report and reference tables ( Annex 1), racks with test tubes, trays, flasks for waste, hourglass, indicators - phenolphthalein and litmus, solutions of barium chloride, iron (II) sulfate, sodium carbonate, sulfuric acid, silver nitrate, red blood salt, sodium hydroxide, calcium chloride, copper (II) sulfate, calcium hydroxide, hydrochloric acid. To solve problems on the recognition of substances, students are given solutions of sulfuric acid, calcium hydroxide and calcium chloride in numbered bottles.

Lesson structure:

• Organizing time. 1 minute.
• Motivation. 1 minute.
• Repetition of methods for the determination of cations and anions in solutions. 2 minutes.
• Report on the order of the experiments and the evaluation of the work. 2 minutes.
• Reminder of the structure of the programmed teaching aid. 1 minute.
• Completing assignments using a programmed teaching aid. 35 minutes
• Summarizing. 3 min.

During the classes

Motivation. A whole science is involved in the recognition of substances, the proof of their composition - analytical chemistry. It employs more people than chemical production.

Repetition. Let's recall the methods for determining cations and anions in solutions (you can use the issued reference materials):

• flame coloration (the only way to detect sodium). The teacher shows a fragment of the video;
• precipitation reactions (little and insoluble substances are formed - white or colored precipitates);
• color reactions - usually a change in the color of indicators in acidic and alkaline solutions;
• reactions with the release of gases, such as carbon dioxide. The teacher conducts demonstration experiments.

The sequence of work.

You have to complete 4 experiences yourself. For each of the first three, 7 minutes are allotted. If the time required is longer, the third experiment can be skipped. Use an hourglass to control the time. At the end of the lesson, you give the teacher the answer to the substance recognition problem (test 4) in the form of two completed tables. At the end of the lesson, you get two marks: for completing the test experience and for completing all the work.

Sequence of work with programmed manual(Table 1). You read the first task, printed on the left page of the manual spread at the top, and write on this page the missing word, the formulated answer, the reaction equation. On the left side of the right-hand page of the spread, separated by a vertical line, the necessary explanations and pictures are provided to help you arrive at the correct answer. After completing the task, turn the page and on the right side of the next spread, find the answer and compare the one you wrote down with the correct one printed under the same number.

After receiving confirmation of the correct answer, you can proceed to the next task, which is printed at the top of the left page of the next spread and has a number one more than the previous one.

Read the safety precautions before testing.

Safety regulations:

• Substances should not be taken by hand, taste and odor should not be tested.
• Do not mix unknown substances unless instructed by your teacher.
• When performing experiments, use small doses of substances.
• Handle acids and alkalis with care.
• If solutions come into contact with hands or clothing, wash immediately with plenty of water.
• Wash your hands with soap and water after handling.
• Use only clean laboratory glassware.
• Do not pour out residues of substances or pour back into the container with pure substances.

I have read the safety regulations ………………… (signature)

Table 1

Programmed manual

Left page spread of the manual	The right page spread of the manual
The task	Explanation of the task	Answer
Test 1 Confirm the quality composition of barium chloride 1. In an aqueous solution, barium chloride dissociates into ions BaCl 2 = Ba 2+ + 2Cl - Therefore, it is necessary to prove the presence of cations in the solution with the help of qualitative reactions ……. and anions ... ...
2 ... According to table 2 ( Annex 1) select the appropriate reagents The reagent for barium cations is …… - anion, …… The reagent for chloride anions are cations ……		1 . Cl - (chloride - anions)
3 ... To carry out the reaction, pour into two test tubes two samples of the initial solution with a volume of 0.5 ml each 4. Add to the first tube a colorless transparent solution of sulfuric acid ... ... containing sulfate - anions BaCl 2 + H 2 SO 4 = BaSO 4 + 2HCl Ba 2+ + 2Cl - + 2H + + SO 4 2- = BaSO 4 + 2H + + 2Cl - Ba 2+ + SO 4 2- = BaSO 4 Checking the equations by the sum of the coefficients: in the molecular equation …… in the complete ionic equation …… in the abbreviated ionic equation ……		2 . sulfate -, SO 4 2- silver, Ag +
5 ... Add to the second tube the silver nitrate solution ... ... containing silver cations Formed ... ... precipitate as a result of the reaction BaCl 2 + 2AgNO 3 = Ba (NO 3) 2 + 2AgCl Ba 2+ + 2Cl - + 2Ag + + 2NO 3 - = Ba 2+ + 2NO 3 - + 2AgCl Ag + + Cl - = AgCl The sum of the odds: in the molecular equation …… in the complete ionic equation …… in the abbreviated ionic equation ……		4 .
Conclusion Using precipitation reactions, we proved that the barium chloride solution contains cations ... ... and anions ... ..., thereby confirming the composition of the given salt		5 . white cheesy
Test 2 Confirm the qualitative composition of ferrous sulfate (II) FeSO 4 = Fe 2+ + SO 4 2- Therefore, it is necessary with the help of qualitative reactions to prove the presence of cations ... ... and anions ... ...
2 ... According to tables 2 and 3 ( Annex 1) select the appropriate reagents The reagent for doubly charged iron cations is an alkali solution containing …… - anions or a solution of red blood salt …… The reagent for sulfate - anions are barium cations ……		1 . SO 4 2-, sulfate anions
3 ... To carry out the reaction, pour into three test tubes three samples of the initial solution with a volume of 0.5 ml each 4. Add sodium hydroxide solution to the first tube A precipitate is formed ... ... color as a result of the reaction FeSO 4 + 2NaOH = Na 2 SO 4 + Fe (OH) 2 Fe 2+ + SO 4 2- + 2Na + + 2OH - = 2Na + + SO 4 2- + …… Fe 2+ + 2OH - = ……		2 . OH -, hydroxide -
5 ... Add K 3 red blood salt solution to the second tube A precipitate is formed ... ... color as a result of the reaction 3FeSO 4 + 2K 3 = 3K 2 SO 4 + Fe 3 2 3Fe 2+ + 3SO 4 2- + 6K + + 2 2- = 6K + + 3SO 4 2- + Fe 3 2 3Fe 2+ + 2 2- = Fe 3 2 The sums of the coefficients in the above equations are respectively equal to ……, ……, …… (When performing control work, only one qualitative reaction is carried out for the determined ion)		4 . greenish
6 ... Add the barium chloride solution ... ... to the third tube. A precipitate is formed ... ... color as a result of the reaction FeSO 4 + BaCl 2 = BaSO 4 + FeCl 2 Fe 2+ + SO 4 2- + Ba 2+ + 2Cl - = BaSO 4 + Fe 2+ + 2Cl - …… + …… = …… The sums of the coefficients in the above equations, respectively ……, ……, ……		5 .
Conclusion Using precipitation reactions, we proved that iron (II) sulfate contains a cation ... ... and an anion ...		6 . Ba 2+ + SO 4 2- = BaSO 4 v
Test 3 Confirm the quality composition of sodium carbonate 1. In an aqueous solution, this salt dissociates into ions Na 2 CO 3 = …… + …… Therefore, it is necessary with the help of qualitative reactions to prove the presence in the solution of cations ... ... and CO 3 2- (... ... - anions)
2 ... According to tables 1 and 2 ( Annex 1) select the appropriate qualitative reactions Sodium is determined by the coloration of the colorless flame of a gas burner (the experiment is not carried out during the performance of the work). The reagent for carbonate anions are cations …… and acid solutions containing cations ……		1 . Na + and (carbonate anions)
3 ... To carry out qualitative reactions to carbonate ions, pour samples of the initial solution with a volume of 0.5 ml each 4. Add to the first tube a solution of calcium chloride …… (or calcium hydroxide ……) containing cations …… A white precipitate is formed, which dissolves when hydrochloric acid is added ... ... (in this case, bubbles of transparent colorless gas appear in the test tube) When a precipitate forms, the reaction proceeds Na 2 CO 3 + CaCl 2 = 2NaCl + CaCO 3 2Na + + CO 3 2- + Ca 2+ + 2Cl - = 2Na + + 2Cl - + CaCO 3 …… + …… = …… The sum of the coefficients in the equations, respectively ……, ……, …….		2 .
5 ... Add the hydrochloric acid solution to the second tube ... ... An odorless gas is released, causing the lime water to cloud (evidence of CO 2 evolution: moisten the glass with a calcium hydroxide solution and hold over the tube until cloudy) Na 2 CO 3 + 2HCl = 2NaCl + CO 2 + H 2 O 2Na + + CO 3 2- + 2H + + 2Cl - = 2Na + + 2Cl - + CO 2 + H 2 O 2H + + CO 3 2- = CO 2 + H 2 O Coefficient sums ……, ……, ……		4 . CaCl 2 or Ca (OH) 2 Ca 2+ (calcium) Ca 2+ + CO 3 2- = CaCO 3 v
Conclusion Using the precipitation reaction and the outgassing reaction, we have proven that sodium carbonate solution contains …… - anions CO 3 2-		5.
Experience 4.(The task of recognizing substances) Recognize by means of characteristic reactions the solutions of sulfuric acid, calcium hydroxide and calcium chloride, which are in three numbered vials (To recognize means to determine empirically what substance is in each of the vials) 1. Substances in the dispensed solutions belong respectively to the classes ……,….… And ……, and are (strong / weak) …… electrolytes In an aqueous solution, these substances dissociate into ions H 2 SO 4 = 2H + + SO 4 2- Ca (OH) 2 = Ca 2+ + 2OH - CaCl 2 = Ca 2+ + 2Cl - Therefore, it is necessary, using qualitative reactions, to prove the presence of the following cations in the solution: H +, Ca 2+, and anions: SO 4 2-, OH -, Cl -
2 ... According to tables 2 and 3 ( Annex 1) choose the appropriate reagents Detected ion: Reagent: hydrogen cation H + …… calcium cation Ca 2+ ... ... hydroxide - anion OH - …… sulfate - anion SO 4 2- …… chloride - anion Cl - ……		1 . base - (alkali) strong
3 ... To carry out the reactions, pour into three clean tubes, 0.5 ml of each of the three samples. Using the dissolution table, select the sequence for adding reagents so that in one experiment you can have a precipitate in only one tube: 5 …… (experience may not be available)		2 . CO 3 2-, Na 2 CO 3 litmus or phenolphthalein
4 ... Add reagent # 1 to three sample tubes. Record the observations in Worksheet 2. 5. Add reagent # 2 to three new sample tubes. Record your observations in Table 2. If you have established the qualitative composition of one of the samples using reagents 1 and 2, you can write it down in the corresponding line at the bottom of the table. No further experiments are carried out with this sample. 6. Add reagent # 3 to the remaining samples. Record observations Continue working with reagents # 4 and # 5 by analogy.		3 . 1 or 2 - BaCl 2 2 or 1 - litmus 3, 4, 5 - your options
7 ... Complete tables 2 and 3 and submit for review

Homework. In addition to the abbreviated ionic equations of Test Worksheet 4, write the molecular and complete ionic equations in a notebook.

table 2

Results of solving the recognition problem

Table 3

Recognition task completion report (test 4)

Carry out reactions confirming the qualitative composition of sulfuric acid. Write down the reaction equations.

Place 1-2 zinc granules in a test tube and pour about 1 ml of diluted sulfuric acid into it. What are you seeing? Write the equation for the reaction and consider redox processes.

Pour sodium sulfide solution into two tubes. Pour chlorine water into one of them, and bromine water into the other. What are you seeing? Explain your observations. Write the equations of the corresponding reactions in molecular and ionic forms.

Chlorine and bromine water are oxidizing agents, so in both test tubes the sulfide is oxidized to sulfur.

Solutions are discolored.

You have been given three test tubes of solutions. Determine which one contains hydrochloric acid, sulfuric acid and sodium hydroxide. Write the equations of the corresponding reactions in molecular and ionic forms.

Determine if table salt contains sulfates. Write the reaction equations in molecular and ionic forms.

With the help of characteristic reactions, determine whether the salt given to you is sulfate, iodide or chloride. Write the equations of the corresponding reactions in molecular and ionic forms.

Starting from copper (II) oxide, get a solution of copper (II) sulfate and isolate crystalline copper sulfate from it. Write the equations of the corresponding reactions in molecular and ionic forms.