PRACTICAL WORK "PREPARATION OF SOLUTIONS WITH
A CERTAIN MASS FRACTION OF THE DISSOLVED SUBSTANCE".

LESSON OBJECTIVES:
- consolidation of skills and abilities in the preparation of solutions with a certain
- mass fraction solute;
- to continue the formation of skills of weighing substances and measuring the volume of liquid;
- the formation of interest in the subject.
EQUIPMENT: scales, weights, beakers, glasses, glass rods, brushes. Reagents: water, Na 2 CO 3 . TV cards. Task cards for practical work. Leaflets with "traces of a criminal" (cryptoscript with a solution of phenolphthalein). Cards with additional tasks. Sequence diagram
work. Algorithm for solving problems.
DURING THE CLASSES.
1. introduction teacher (about the objectives of the lesson).
Anninsky Meat Processing Plant made a statement about the loss of all table salt. The production of meat products is in jeopardy. We need to find the criminal as soon as possible, who, like any violator of the law, left traces at the crime scene. To perform such a difficult job is entrusted to the departments of programmers, forensics and analysts. Each department must prepare
sodium carbonate solution and use it to determine the trail of the offender.
Together we will find out who is the salt thief.
2. Safety briefing. Frontal conversation about safety regulations, rules for weighing, measuring the volume of liquids and dissolving substances.
3. Updating knowledge about solutions. Conversation on:
- what is a solution?
What is the mass of the solution?
How is the mass fraction of a solute calculated?
4. Application of knowledge and skills. Students solve problems, determine the mass of salt and volume of water, prepare a solution. When the solution is prepared, it is used to develop a drawing on paper made with a solution of phenolphthalein. Each group writes their findings on the board.
Students who complete the task receive an additional task "Top Secret" varying degrees difficulties.
Note. During the practical part, students work in various groups:
1) analysts do all the work on their own, do not have the right to consult a teacher;
2) criminologists have a diagram that reflects the main stages of work, they are entitled to one hint;
3) programmers have a scheme that reflects the main stages of work, and an algorithm for solving the problem of calculating the mass of a substance and the mass of water needed to prepare a solution.
Summing up the work. Identification of the "criminal" (H 2 O).
5. Homework.
Calculate the mass fraction of sugar in your tea, if in 1 teaspoon
contains 10 g of sugar.
6. Cleaning jobs.
Appendix.
Task for a group of analysts.
2. Determine the purpose of your work.
3. Solve the problem.
4. Prepare the solution.

Task for a group of criminalists.
1. Write down the number and title of the practical work.
2. Determine the purpose of the work.
3. Solve the problem:
a) Briefly write down the condition of the problem.
b) calculate the mass of the substance using the formula:

m (in-va) \u003d (w (in-va) m (p-ra)) / 100%

c) calculate the mass of water using the formula
m (H 2 O) \u003d m (r-ra) - m (in-va)

5. Prepare the solution.

Task for a group of programmers.
1. Write down the title of the practical work.
2. Determine the purpose of the work.
3. Solve the problem:
a) short condition tasks:
Given:
m (r-ra Na 2 CO 3) \u003d 20g
w(Na 2 CO 3)=5%

To find:
m(Na 2 CO 3)
m(H 2 O)
b) calculate m (Na 2 CO 3) using the formula

m(Na 2 CO 3) = (m(p-pa Na 2 CO 3) w(Na 2 CO 3)) / 100%

c) calculate the mass of water using the formula:

m (H 2 O) \u003d m (p-pa Na 2 CO 3) -m (Na 2 CO 3)

4. Prepare the solution.

Additional tasks "Top Secret".
1. Calculate the mass fraction of sodium chloride, if in 100 g of solution
contains 5 g of sodium chloride.
2. Calculate the mass fraction of sodium chloride if dissolved in 80 g of water
20 g sodium chloride.
3. 20 g of water was added to 100 g of a 5% sodium chloride solution.
Determine the mass fraction of the resulting solution.

Name: Practical work"Preparation of solutions with a certain mass fraction of a solute"

Position: teacher of chemistry and biology
Place of employment: MKOU Verkhnetishanskaya secondary school named after V.A. Fufaeva
Location: Voronezh region Talovsky district

Contest rules:


- Photo contests

Extracurricular work:



- KVN



- Working with parents




- Materials for certification

School items:


- Astronomy (class 11)
- Natural history (class 5)
- Biology (grades 5-11)


- Civics (class 5-7)
- Natural science (grades 9-11)

Technological map of lesson No. 20

FULL NAME. teachers : Govoruha O.V.

Grade: 5

Thing: technology

Number of hours : 1

Lesson topic : "Preparing a dish of boiled vegetables."

The purpose of the lesson: Familiarization of students with the types of heat treatment of vegetables; formation important rules heat treatment; requirements for the quality and design of finished dishes.

Lesson objectives:

1) To acquaint students with the main types of heat treatment of vegetables.

2) To teach students how to properly heat-treat vegetables and cook boiled vegetable dishes

3) To instill in students an interest in the art of cooking, accuracy, organization, independence and aesthetic taste, the ability to carefully and economically use products, keep in order workplace when preparing dishes from boiled vegetables.

Lesson type: Practical work

Educational Resources: Teaching materials for technology textbook grade 5 N.V. Sinitsa, V.D. Simonenko; workbook, a computer, a presentation, a set of tableware and appliances for preparing a salad of boiled vegetables, instruction cards, posters.

Planned educational outcomes:

subject - students will learn about the methods of heat treatment of vegetables by the technology of making vinaigrette, get acquainted with the requirements for the quality and design of ready-made dishes from boiled vegetables.

Metasubject (UUD):

- regulatory - determination of the technological sequence of salad preparation.

communicative - the ability to work in a group when completing a task, the ability to cooperate with the teacher, to allow conflict situations adequately perceive and develop a respectful attitude towards peers in the course of joint work.

- cognitive - selection of the most rational ways of cooking and conduct a comparative analysis.

Personal – promotereadinessto rational housekeeping,the ability to conduct self-analysis of the work performed, to develop industriousness, to cultivate accuracy and neatness in work.

№ stage of the lesson

Lesson stage

Teacher activity

Student activities

Formed UUD

Org. Moment.

Checking knowledge on the topic of the previous lesson.

Greeting children. Obtaining information about absentees. Preparation for the lesson (textbook, notebook, pen, diary).

Repetition of the material covered:

2. How to determine the readiness of vegetables when cooking?

3. What determines the shape of the names of vegetables?

4. Message, which means the word "vinaigrette".

Children's answers.

1. To reduce the loss of vitamin C, vegetables are boiled in a container with a closed lid.

2. Vegetable must be pierced with a knife or fork; it should be soft.

3. The shape of the vegetable name depends on the type of salad.

K. development speech activity, gaining experience using speech means for the regulation of mental activity.

Motivation (self-determination)

to learning activities.

Let's continue the lesson.

1. What should we learn in this lesson.

2. What tasks will we set.

Cooking Safety

TB when using an electric stove.

1) Before turning on, check the condition of the power cord.

2) When turning on the stove, insert the plug into the socket sockets until it stops. Do not disconnect the plug by pulling on the cord.

3) Use fireproof cookware for cooking vegetables. It is forbidden to use plastic utensils.

4) Make sure that when boiling, the contents of the dishes do not spill over the edge, take the lids of hot dishes with a towel or potholder and open them away from you.

TB when using cutting tools.

1) Take the utmost care when cutting vegetables with a knife.

2) Pass knives and forks only with the handle forward.

3) Cut vegetables on cutting boards, observing right tricks cutting. The fingers of the left hand should be bent and placed at some distance from the blade of the knife.

4) Exercise caution when working with hand graters. Hold the processed foods (fruits, vegetables) tightly, do not process too small parts.

Work sequence

1) Put on work clothes (apron, scarf or cap)

2) Wash your hands with soap.

3) Study the technological map

4) Organize the student's workplace

5) Prepare the dish according to the technological map.

6) Perform table setting.

7) Serve the cooked dish.

8) Clean up your study place.

1. Learn how to cook a salad of boiled vegetables. 2. Learn to cut boiled vegetables into cubes.

3. Observe the sanitary and hygienic requirements for cooking and safety rules when working with a knife.

Describe safety precautions in cooking

L. Self-determination, self-organization,

J. Planning for collaborative collaboration with peers and with the teacher.

P. The ability to predict activities in the lesson

Actualization of knowledge and fixation of individual difficulties in a trial action.

Invite students to study the technology of making vinaigrette according to the proposed technological map.

Appendix Vinaigrette preparation sequence, salad preparation flow chart.

Make assumptions study the technological map

P. extract necessary information from texts

R. trial run educational action

K. taking into account different opinions, expressing one's thoughts with sufficient completeness and accuracy

Practical work "Cooking vinaigrette"

The teacher distributes the actions of the students.

While making the vinaigretteteacher draws the attention of students to reminders and tips that are as hints in the area of ​​​​practical work, in places accessible to the eyes.Appendix

When eating foodteacher monitors compliance with the rules of conduct at the table and the rules for the use of cutlery.

Time to finish preparing the dish, clean up the workspaces, start tasting.

They put on headscarves and aprons, go to the dining room to do practical work.

Pupils prepare a salad, showing practically slicing vegetables using technological map salad preparation.Appendix

Ready, beautifully decorated salad is put on the table. Pupils sit down at the table, evaluate appearance dishes using the card evaluating the finished dish.Appendix

After eating, students wash and return the dishes.

R. determination of the technological sequence of salad preparation.

K - the ability to work in a group when performing a task, the ability to cooperate with the teacher, resolve conflict situations, adequately perceive and develop a respectful attitude towards peers in the course of joint work.

P. the choice of the most rational ways of cooking and conduct a comparative analysis.

Primary consolidation with pronunciation in external speech.

1. What is the sequence of making vinaigrette?

2. How can you decorate a vinaigrette?

3. What rules should be followed when preparing a vinaigrette?

Answer questions, talk about their difficulties

P.analysis, synthesis, generalization, classification.

K. formation and argumentation of one's opinion and position of communication, management of the partner's behavior.

L. Awareness of responsibility for a common cause.

Reflection of educational activity.

Let's sum up the lesson.

Choose and continue with any offer.

In today's lesson, I learned...

In this lesson, I would commend myself for…..

After class, I wanted...

Today I managed...

Thank you for the lesson!

Home Find out how steam cooking takes place, what device you need to have for this. Complete the tasks in the workbook.

P.reflection of methods and conditions of action, control and evaluation of the process and result of activity.

L. Self-assessment based on the criterion of success, an adequate understanding of the reasons for success and failure in educational activities.

K. planning of educational cooperation.

Silvanovich Marina Sergeevna

Chemistry teacher

KSU "Bastomar secondary school"

The purpose of the lesson: to form the ability to prepare a solution of a given concentration.

- fixing theoretical knowledge about solutions and ways of expressing their concentration;

– Improving the skills of working with laboratory equipment and the ability to solve calculation tasks to determine the concentration of the solution;

- fostering accuracy, observation and a culture of safe behavior in the chemistry room.

Equipment: training scales with weights, a conical flask, a measuring flask, a measuring cylinder, a glass rod, a sheet of paper, a crystal salt.

During the classes.

1. Organizational moment.

2. Actualization of knowledge.

In past lessons, we said that solutions are an integral part of our lives.

- Guys, remember what a solution is? ( homogeneous system, consisting of solvent particles and solute particles.)

Do you remember the importance of solutions? (Student answers: almost all medicinal substances act on the body in a dissolved state, the assimilation of food is associated with the transfer of nutrients into a solution; solutions are the most important physiological fluids - blood, lymph, plant cell sap, etc.; obtaining fertilizers, metals and their alloys, paper, perfumes flow in solutions).

Today in the lesson we will carry out practical work on preparing a solution with a certain mass fraction of a solute.

What is the purpose of our lesson? (children independently formulate the goal of practical work).

AT Everyday life we often come across solutions: when preparing pickles, compotes, when using medicines. Many professions are associated with solutions: pharmacist, nurse, confectioner, chemistry teacher, laboratory assistant.

Today in the lesson we will learn in practice how to prepare a solution of the desired concentration.

1. What are the components of the solutions? (solvent, solute)

2. What makes up the mass of the solution? (mass of solvent and mass of solute)

3. What does the mass fraction of a solute show?

4. 50 g of milk powder was dissolved in 150 g of water. The mass fraction of the solute in the solution is equal.

5. To prepare 500 g of a 2% milk drink, you need to take a lot of water.

3. Doing practical work.

- Organic chemist N.N. Semenov wrote: "Chemistry is an experimental science, not a magical one, and it is better to be safe in this science than to regret later."

Safety regulations.

When carrying out any practical work, you and I must comply with safety regulations.

(Students take turns explaining the rules of TB to the whole class during practical work).

Remember every student, Know, any crumb, Safety is good, And negligence is bad!

Do not rush to grab a test tube, Read the instructions, Make sure you understand everything, That's when you start!

For the experience to work, use clean dishes!

Let it smell like roach in a test tube, Like marmalade in a flask, Do not taste substances! Even poison smells sweet!

Practical work number 4:

Preparation of salt solutions with a certain mass fraction of the dissolved substance

The purpose of the work: to prepare a solution with a given mass fraction of the solute

Equipment. Technical scales with weights, a chemical beaker, a measuring cylinder, a spoon for bulk substances, a glass rod.

Reagents: table salt - NaCl, distilled (boiled) water - H2O.

Working process:

1. Calculation of the mass of the necessary substances for the preparation of the solution.

* From the proposed conditions, choose one and calculate the masses of water and salt.

OPTION 1.

Prepare 25 g of 4% sodium chloride solution.

OPTION 2.

Prepare 20 g of 5% sodium chloride solution.

OPTION 3.

Prepare 25 g of 2% sodium chloride solution.

2. Measurement of mass of salt and volume of water

* Balance the scales with a sheet of paper.

* Install a weight on the right pan of the scales, pour salt on the left pan until it balances.

* Pour salt into a conical flask.

* Measure required amount water using a graduated cylinder (mH2O=VH2O)

* Pour water into a conical flask.

3. Solution preparation

* Stir the salt and water in a conical flask with a glass rod until the salt is completely dissolved.

* Pour the resulting solution into a graduated cylinder and measure the volume of the solution.

* Hand over the prepared solution to the teacher.

4. Registration of work

4. The result of the lesson, grading.

5. Homework.

Practical work No. 1

"Preparation of a salt solution with a certain mass fraction of a solute"

Target: learn how to prepare a salt solution with a certain mass fraction of a dissolved substance, improve skills in working with laboratory equipment.

Reagents: crystalline salts, potassium chloride, sodium nitrate, sodium chloride, distilled water.

Equipment: technochemical scales with weights, beaker, glass rod, spatula.

Safety rules during practical work

For pouring solids spatula should be used. Do not take reagents with unprotected hands. To stir the liquid in a glass beaker should be stirred with a glass rod. When working with glass, you must be careful, especially you need to protect your eyes.

Work order

1. Calculate the masses of salt and water that must be taken for cooking certain solution. Mass fractionwis the ratio of the mass of the solute to the mass of the solution. Expressed as a percentage.

We determine the mass of the solute (salt), which is necessary to prepare the solution according to the formula:

m (races) = w

We find a mass of water. Since the mass of a solution consists of the mass of the solute and the mass of water, the mass of water is equal to the difference between the mass of the solute and the mass of the solution.

We calculate the volume of water, since it is impossible to weigh water on a scale. The density of water at +25°C is 1 g/cm 3 .

V =;

After calculating the mass of salt and the volume of water, it is necessary to weigh the required mass of salt on a balance. For this, technochemical scales are used, which give results with an accuracy of 0.01 g.

2. We measure the required volume of distilled water using a graduated cylinder. Pour distilled water into the measuring cylinder so that the lower level of the substance touches the selected mark. During the measurement, the cylinder must be in a vertical position, and the eyes of the observer and the volume value at the same distance.

3. Pour a measured volume of water into a beaker with salt. Gently stir the contents with a glass rod until the salt is completely dissolved.

We make a report in the following form:

We calculate the mass of salt and the volume of water required to prepare the solution.

Weigh the salt of a certain mass on the scales and pour it into a beaker.

We measure the required volume of water with a measuring cylinder and pour it into a beaker.

Stir the contents of the beaker with a glass rod to dissolve completely.

Tasks

A) prepare 20 g of a solution with a mass fraction of potassium chloride of 0.05;

B) prepare 25 g of a solution with a mass fraction of sodium nitrate of 4%;

C) prepare 10 g of a solution with a mass fraction of sodium chloride of 10%;

Observations: the salt has dissolved.

Findings: a salt with a solute is taken. In this solution, salt is the solute, water is the solvent.

General conclusion of the work: during the practical work, they learned how to prepare a salt solution with a certain mass fraction of a dissolved substance, improved their skills in working with laboratory equipment.

Goals:

1. Be able to prepare solutions with a certain mass fraction of a solute using the following operations: weighing, measuring a certain volume of liquid, dissolving; make the necessary calculations; know calculation formula to determine the mass fraction of a dissolved substance, rules of use chemical glassware and reagents.

2. Cultivate conscious discipline during practical work. To develop a dialectical worldview, to cultivate a communicative culture of students, to form the ability to organize work.

3. Create conditions for the development of logical thinking, intellectual skills.

Equipment: Technical scales with weights, a chemical beaker, a measuring cylinder, a spoon for bulk substances, a glass rod, a bottle for the prepared solution.

Reagents: H 3 BO 3, NaHCO 3, KMnO 4 - all crystalline, distilled (boiled) water.

During the classes:

1. Organizational moment

2. Preparation for the implementation of practical work.

Safety regulations

Handle chemical equipment with care!
Use clean and workable utensils.

3. Progress of work.

Target: Consolidate knowledge on the topic "Solutions", develop skills in solving problems for finding the mass fraction of a substance, handling chemical reagents.

Modulo movement scheme

UE-1: entrance control

Target. Test knowledge and readiness for practical work.

We work in a notebook for practical work.

EXERCISE

I option

1. Mass fraction - a physical quantity that is measured:

a) in liters;
b) in grams;
c) as a percentage;
d) in moles.

2. What is called the meniscus?

(1 point)

3. What is the mass fraction (in%) of potassium hydroxide in a solution containing 40 g of KOH in 200 g of water?

a) 16.7;
b) 20;
c) 40;
d) 33.4.

II option

1. Mass fraction - a physical quantity, which is denoted:

a) m;
b) w;
c) V;
d) M.

2. What meniscus does water give in a glass vessel?

3. What is the mass fraction (in%) of potassium hydroxide in a solution containing 20 g of KOH in 180 g of water?

a) 16.7;
b) 20;
at 10 o'clock;
d) 33.4.

Check your answers on the board.
If you scored 0 points, then when performing UE, use a notebook with notes.
If you scored 1 point, go to UE-2.
If you scored 2 points, go to UE-3.
If you scored 3 points, go to UE-4.

Target. To develop the ability to select weights for weighing a substance of a certain mass.

Exercises.

1. Select weights for weighing 6.25 g of the substance (5 g + 1 g + 0.2 g + 0.05 g = 6.25 g).

2. Select weights for weighing 3.64 g of substance 2g + 1g + 0.2g + 0.2g + 0.2g + 0.02g + 0.02g

Target. Develop problem solving skills for finding the mass of a solute in a solution.

I option

What mass of sodium bicarbonate must be taken to prepare a solution of 20 g with a mass fraction of salt of 2%? Where is this solution used?

Answer: m (NaHCO 3) \u003d 0.4 g. The resulting solution is used to treat the skin if acid gets on it.

II option

Determine the mass of boric acid required to prepare 50 g of a solution with a mass fraction of acid of 0.02. Where is this solution used?

Answer: m (H 3 BO 3) = 1 g , Boric acid solution is used in medicine as a disinfectant. In the laboratory, it is stored in the first-aid kit for rinsing the eyes in case of contact with alkali.

Target. To consolidate practical skills in preparing a solution with a given mass fraction of a solute in a solution.

For burns electric shock apply a bandage moistened with a 1% solution of potassium permanganate KMnO 4 . Prepare 80 g of this solution.

Target. Evaporated 150 g of 15% sugar solution. How much sugar is left in the cup after evaporation?

Give the practice book to the teacher. Tidy up your workspace.

Reflection

Return to lesson objectives. Have you reached them in the course of your work? Evaluate your work in three areas: "I", "we", "business".