Gavrilova Elena Ivanovna
Chemistry teacher of the highest qualification. categories.
MBOU BSOSH No. 1 named after. P.P. Koryagina
Item . Chemistry.
Lesson topic: " Mass fraction of element".
8TH GRADE.
UMK G.E. Rudzitis.
Lesson type: Learning new material
Target : Develop the skill of solving problems on calculating the fraction and finding the mass of a solution component.
Tasks
Educational:
- .Form the concept of the mass fraction of an element;
- To teach how to establish the simplest formula of a substance based on the mass fractions of elements.
Educational:
- To develop logical thinking skills and interest in chemical science among schoolchildren.
Educational:
- Develop a personality with an ecological way of thinking.
- Foster a sense of camaraderie and responsibility in students.
Planned learning outcomes:
subject:
- formation of systematized knowledge about the proportion of an element in a substance;
- development of the ability to calculate the mass fraction of various substances;
meta-subject:
- developing competence in the use of acquired knowledge in other academic disciplines;
personal:
- formation of conviction in the necessity of chemical knowledge for human life;
Means of education:
- Multimedia projector;
- Computer;
- Cards;
- The flyleaf of the textbook with the table of D.I. Mendeleev;
- Notebooks;
- Table of D.I. Mendeleev;
- Author's presentation on the topic “Mass fraction of an element in a compound.”
Epigraph for the lesson:
Nature surrounds us with mysteries and, and
an attempt to solve them belongs to
To the greatest joys of life.
W. Ramsay
Lesson steps
Lesson stage | Teacher activities | Student activities |
1. Organizational moment. | Checks the children's readiness for the lesson. Greetings, positive attitude to the lesson. | Check readiness for the lesson. |
2. Goal setting and motivation. | Creating a stimulating and motivating situation through a system of questions: Listed below are various minerals from which iron can be obtained (FeO, Fe 2 O 3 , Fe 3 O 4 ) (on a multimedia projector). Problem question: What mineral do you think is most beneficial to use to obtain iron? | They make their own assumptions about the question posed. |
Organizes the activities of students to formulate the topic and goals of the lesson. What do you think is the purpose of our lesson? | Determine the purpose of the lesson |
|
You have a certain amount of knowledge; what concepts learned earlier will help you achieve your goal? | Chemical element, chemical formula, relative atomic and molecular mass. |
|
3.Updating and monitoring knowledge. | What can we say about these minerals? | Composed of iron and oxygen atoms |
Is it possible to answer the question posed by qualitative and quantitative composition? | Teamwork |
|
Molecular mass of substances |
||
Checking homework | On the given cards, students calculate the molar mass of iron oxides. After completing the task, they exchange cards with their deskmate and check together with the teacher. |
|
3. Studying new educational material. | Organizes a conversation using presentation information, textbook text, and workbook. Controls the “discovery” of new knowledge. Corrects them.
Draws an analogy for calculating the fraction of a substance with mathematics.
Calculate the mass fraction of iron in each substance and answer the question (return to the first slide) Discussion of completed tasks. Does the ore mining process affect the environment? Physical education minute. Let's remember the chemical elements. I tell you the name, if it matches the pronunciation, we raise our right hand, if not, we raise our left hand. Generalization and systematization Introduces new substances that contain the same chemical element. Calculate its mass fraction in each. SO 2 and SO 3 ω (S) = CO 2 and CO ω (C) = ω (N) = HNO 3, HNO 2 Complete the tasks in the workbook to consolidate the material. | Answer the proposed questions. Draw the composition of substances in different colors. Part of the whole. Students remember how the share is calculated in mathematics. Atomic mass of the element Derive the formula of the substance together with the teacher ω=(Аr·n/Мr)·100% They are counting on it. 3 students working at the blackboard Answer the question Make their own assumptions Physical education minute. One of the students, in the direction of the teacher, names the correct pronunciation. Make calculations They do the work. |
4. Reflection and summing up the lesson. | Organizes reflection and summation of the lesson. If your mom asked you to text her about the most important thing in class, what would you write? Have we achieved our goals? Guys, finishing the lesson, please stick the given circle on one of the posters at the exit. (We have learned everything, we haven’t learned enough, serious improvement is required). | Pronounce their answers. They evaluate their work in posters at the exit. |
5.Information about homework. | Offers a task in accordance with the capabilities: 1. Calculate which of the proposed compounds (hydrogen peroxide, water, sulfuric acid, calcium oxide, sodium peroxide - formulas written down by the teacher) has the largest mass fraction of oxygen? 2.Find the mass fraction of each element in the compound (Fe 3 (PO 4 ) 2 *8H 2 O) | They select homework in accordance with their own capabilities and abilities, and their demonstrated interest in the topic being studied. |
Literature used:
1. Chemistry, grade 8, Inorganic chemistry, grade 8, Rudzitis G.E., Feldman F.G., 2017.
2. Workbook. 8th grade.
3. Didactic materials. 8-9 grades.
Obernikhina Tatyana Sergeevna
chemistry teacher of the highest qualification categories.
Municipal educational institution "Secondary school No. 3 of Koryazhma"
Item . Chemistry.
Lesson topic Mass fraction of element.
8TH GRADE.
UMK G.E. Rudzitis.
Lesson type: Learning new material
Target : Develop the skill of solving problems on calculating the fraction and finding the mass of a solution component.
Tasks
Educational:
Form the concept of the mass fraction of an element;
To teach how to establish the simplest formula of a substance based on the mass fractions of elements.
Educational:
To develop logical thinking skills and interest in chemical science among schoolchildren.
Educational:
Develop a personality with an ecological way of thinking.
Foster a sense of camaraderie and responsibility in students.
Planned learning outcomes:
subject:
formation of systematized knowledge about the proportion of an element in a substance;
development of the ability to calculate the mass fraction of various substances;
meta-subject:
developing competence in the use of acquired knowledge in other academic disciplines;
personal:
formation of conviction in the necessity of chemical knowledge for human life;
Means of education :
Multimedia projector;
Computer;
Cards;
The flyleaf of the textbook with the table of D.I. Mendeleev;
Notebooks;
Table of D.I. Mendeleev;
Epigraph for the lesson:
Nature surrounds us with mysteries and, and
an attempt to solve them belongs to
to life's greatest joys.
W. Ramsay
Lesson steps
| Lesson stage | Teacher activities | Student activities |
| 1. Organizational moment. | Checks the children's readiness for the lesson. Greetings, positive attitude to the lesson. | Check readiness for the lesson. |
| 2. Goal setting and motivation. | Creating a stimulating and motivating situation through a system of questions: Listed below are various minerals from which iron can be obtained (FeO, Fe2 O3 , Fe3 O4 ) (on a multimedia projector). Problem question: What mineral do you think is most beneficial to use to obtain iron? | They make their own assumptions about the question posed. |
| Organizes the activities of students to formulate the topic and goals of the lesson. What do you think is the purpose of our lesson? | Determine the purpose of the lesson |
|
| You have a certain amount of knowledge; what concepts learned earlier will help you achieve your goal? | Chemical element, chemical formula, relative atomic and molecular mass. |
|
| 3.Updating and monitoring knowledge. | What can we say about these minerals? | Composed of iron and oxygen atoms |
| Is it possible to answer the question posed by qualitative and quantitative composition? | Teamwork |
|
| Molecular mass of substances |
||
| Checking homework | On the given cards, students calculate the molar mass of iron oxides. After completing the task, they exchange cards with their deskmate and check together with the teacher. |
|
| 3. Studying new educational material. | Organizes a conversation using presentation information, textbook text, and workbook. Controls the “discovery” of new knowledge. Corrects them. How can you graphically represent the written formulas? What is a share? Draws an analogy for calculating the fraction of a substance with mathematics. What is the main quantity in chemistry? What is the atomic mass of iron? How, based on knowledge of atomic and molecular mass, can one derive the formula of a substance? Calculate the mass fraction of iron in each substance and answer the question (return to the first slide) Discussion of completed tasks. Does the ore mining process affect the environment? Physical education minute. Let's remember the chemical elements. I tell you the name, if it matches the pronunciation, we raise our right hand, if not, we raise our left hand. Generalization and systematization Introduces new substances that contain the same chemical element. Calculate its mass fraction in each. SO2 and SO3 ω (S) = CO2 and CO ω (C) = ω (N) = НNO3 , НNO2 Complete the tasks in the workbook to consolidate the material. | Answer the proposed questions. Draw the composition of substances in different colors. Part of the whole. Students remember how the share is calculated in mathematics. Atomic mass of the element Derive the formula of the substance together with the teacher ω=(Аr·n/Мr)·100% They are counting on it. 3 students working at the blackboard Answer the question Make their own assumptions Physical education minute. One of the students, in the direction of the teacher, names the correct pronunciation. Make calculations They do the work. |
| 4. Reflection and summing up the lesson. | Organizes reflection and summation of the lesson. If your mom asked you to text her about the most important thing in class, what would you write? Have we achieved our goals? Guys, finishing the lesson, please stick the given circle on one of the posters at the exit. (We have learned everything, we haven’t learned enough, serious improvement is required). | Pronounce their answers. They evaluate their work in posters at the exit. |
| 5.Information about homework. | Offers a task in accordance with the capabilities: 1. Calculate which of the proposed compounds (hydrogen peroxide, water, sulfuric acid, calcium oxide, sodium peroxide - formulas written down by the teacher) has the largest mass fraction of oxygen? 2.Find the mass fraction of each element in the compound(Fe3 (P.O.4 ) 2 *8H2 O) | They select homework in accordance with their own capabilities and abilities, and their demonstrated interest in the topic being studied. |
Literature used:
1. Chemistry, 8th grade, Inorganic chemistry, 8th grade, Rudzitis G.E., Feldman F.G., 2013.
2. Fadeev G.N. Tasks and tests for self-study in chemistry: a manual for students and teachers. - M.: BINOM. Knowledge Laboratory, 2008.
3. Workbook. 8th grade.
4. Didactic materials. 8-9 grades.
Grade: 8 Subject: chemistry Lesson No. 13 Date: 10.17 / 18.10 Levitskaya E.N.
Lesson topic: Mass fraction of a chemical element.
Target:
Educational: teach how to calculate the mass fraction of elements in a compound using the formula of the compound and establish the chemical formula of a complex substance using the known mass fractions of chemical elements.
Developmental: to develop the ability to establish analogies and use algorithms to solve educational and cognitive problems.
Educational: develop a responsible attitude towards learning.
Equipment: textbook G.E. Rudzitis, F.G. Feldman. Chemistry 8. Moscow “Enlightenment” 2014; PSHE D. I, Mendeleev, algorithms for solving problems, test tasks, cards with tasks.
Lesson type: learning new knowledge
DURING THE CLASSES
Don't let your soul be lazySo as not to pound water in a mortar,
The soul must work
And day and night, and day and night!
(M. Zabolotsky).
Organizational stage
Setting the goals and objectives of the lesson. Motivation for students' learning activities
71% of our planet is occupied by matter, without which there would be no life on our earth. What is this substance? (water) You already know that any substance can be written using a chemical formula. Atoms of chemical elements are located in a molecule in certain mass ratios, i.e. constitute a certain part of the total molecule. How can you calculate what part of a molecule is a chemical element (student suggestions)?
With your help, we determined the topic of our lesson: “Mass fraction of a chemical element in a compound.”
What do you think is the purpose of our lesson (students determine the purpose of the lesson)?
Do you have a certain amount of knowledge, what concepts previously studied will help you achieve your goal (chemical element, chemical formula, relative atomic and molecular mass, fraction)?Let's check if you are ready to learn new material
Updating knowledge
Complete tasks (optional)
1 option
1.What does the notation 2O mean? 2 ?
1) four oxygen atoms 2) two oxygen atoms
3) two oxygen molecules 4) four oxygen molecules
2. Which statement correctly reflects the composition of the carbon dioxide molecule CO 2 ? The carbon dioxide molecule consists
1) from a carbon molecule and an oxygen molecule
2) from a carbon atom and a diatomic oxygen molecule
3) from a carbon atom and two oxygen atoms
4) from a carbon molecule and two oxygen atoms
3. Relative molecular weight of iron(III) oxide Fe 2 O 3 equal to
1) 320 2) 160 3) 480 4) 62
4. What is the mass ratio of copper and oxygen in the compound whose formula is CuO? 1) 2: 1 2) 4: 1 3) 1: 1) 1: 4
Option 2
1. Which notation indicates that a nitrogen molecule consists of two atoms?
1) 2N 2) N 2 3) N 2 O 4) N 2 O 3
2. Which statement correctly reflects the composition of the molecule of nitrogen oxide (IV) NO 2 ? The nitric oxide molecule (IV) consists of
1) from nitrogen atoms and oxygen molecules
2) from a nitrogen molecule and an oxygen molecule
3) from a nitrogen atom and two oxygen atoms
4) from a nitrogen molecule and two oxygen atoms
3. Relative molecular weight of glucose C 6 H 12 O 6 equal to
1) 360 2) 90 3) 180 4) 540
4. What is the mass ratio of sulfur and oxygen in a compound whose formula is SO 2 ? 1) 2: 1 2) 1: 1 3) 1: 2 4) 1 : 4
Primary assimilation of new knowledge
1. After analyzing the solution to problem 3, create an algorithm for solving problems to find the mass fraction of an element in a compound (p. 52).
2.Work at the board.
Initial check of understanding
1. Solve the problem yourself.
80 g of compound contains 32 goxygen.Calculate the mass fraction of oxygen in the compound.
2. Mutual verification against the standard: 
Primary consolidation
Work in pairs
1. Analyze the solution to problem 4.
2. Solve the problem yourself using the example.
Determine the formula of a compound of iron with oxygen, in which the mass fraction of iron is 70%.
3. Checking against the standard (writing on the board)
Information about homework, instructions on how to complete it
GENERAL:§ 15, test tasks.
DIFFERENTIATED: ex. 1-7 (optional)
Reflection (summarizing the lesson)
Guys, why do you think I chose the words of the Russian writer M. Zabolotsky as the epigraph for the lesson? You're right! There are no people to whom knowledge comes on its own; only systematic work raises them a step higher every day. If you are unhappy with yourself today, don’t be upset, work at home on your own, and tomorrow you will succeed.
PLAN – CONS PECTURE
kh and m and in 7th grade with the topic:
« MASS FRONT OF ELEMENTS
V O ZH N O M E S T V E.
DECISION TASK »
First qualification teacher
Lesson topic: Mass fraction of an element in a complex substance. Solutions
tasks.
The purpose of the lesson: generalize and systematize knowledge about chemical formulas,
qualitative and quantitative composition of substances; develop skills
solving problems using the mass fraction of an element in a substance; become familiar with methods of finding formulas of substances using data on the mass fractions of elements.
Equipment: periodic system of chemical elements by D.I. Mendeleev, cards with tasks for frontal work, algorithms.
Basic concepts and terms: relative formula and relative molecular weight, mass fraction of an element, simple and complex substances,
chemical formula.
Lesson type: deepening and adjusting knowledge, consolidating practical skills.
Methods and techniques: explanatory and illustrative; practical: problem solving; reproductive; partially search engines.
Lesson structure
I. Organizational stage
II. Checking homework
III. Updating students' basic knowledge
IV. Generalization and systematization of student knowledge
V. Homework
VI. Summing up the lesson
During the classes
“The ability to solve problems is an art that is acquired with practice”
1. Organizational stage
Today we will climb to the top of knowledge, acquire practical skills to use this knowledge, and do everything possible to prevent knowledge from becoming that unfortunate pile of stones. Are you ready for an exciting climb? Do you have a desire to conquer peaks? Please show your mood with the help of cards - “emoticons”.
II. Checking homework.
To successfully climb to the top of knowledge, you must be well prepared, have the necessary knowledge and skills that are needed to master the material. Let's check how ready we are to climb to the top, to perceive new knowledge. What knowledge do we already possess, and what do we need to master?
Completion of written homework assignments is checked.
Task No. 1
Task №2
m(Na) : m(Br) =23:80
Task №3
m(P) : m(H) =31: 3
Task №4
m(Cr) : m(O) = 52:48 = 26:24 =13:12
III. Updating students' basic knowledge
We are gradually beginning to rise to the top of knowledge. But for such a difficult path, we need to have tools, that is, remember some information that will be needed when studying the topic.
Give a definition of the concept “relative molecular weight”. How is it calculated?
Give a definition of the concept “mass fraction of an element in a substance.” How is it calculated?
Write down formulas to calculate the mass fraction of an element and the mass of an element.
What quantities do you need to know to calculate the mass fraction of an element using its chemical formula?
How to find relative atomic mass?
What data are used to write chemical formulas?
IV. Generalization and systematization of student knowledge
Before us is the pinnacle of knowledge. In the last lesson, we already mastered the basic techniques for solving problems using the formula of matter, and each of you has reached some heights at this peak. Some are at the foot of the mountain (middle level), who have reached the very peak - the pinnacle of knowledge. And today we must rise as high as possible, learn to find the mass fractions of elements in substances, calculate the masses of elements from their mass fractions, find formulas of substances from data on the mass fractions of elements.
Look at the climber at the foot of the mountain. Do you think it takes effort for him to climb the mountain? And if you move effortlessly along the mountain, where can you get? Therefore, today in the lesson, in order not to slide down, we will need to put a lot of effort into solving the exercises, be attentive and persistent in our work.
1. Solving problems using the concept of “mass fraction of an element”
Algorithm 1
1.Write down an abbreviated condition of the problem. 2. Determine the relative molecular or formula mass of a substance. 3. Determine the mass fraction of the desired element of the substance using the formula. 4.Write down the answer.
To determine the mass fraction of an element in a compound, use the formula:
ω% (E) = 
Where ω% (E) is the mass fraction of the element in the compound;
n is the number of atoms of the element in the compound;
Ar (E) – relative atomic mass of this element;
Mr (substance) is the relative molecular mass of a given compound.
Problem 1. a). Malachite is a brittle green mineral with the formula CuCO 3 (OH) 2. It is considered a Russian stone; its fame began in 1635. - after the discovery of the Ural malachite mines, which are now completely exhausted. Determine the mass fraction of all elements in this compound.
b) Magnesite has the formula MgCO 3. Calculate the mass fractions of elements in the mineral.
c) Emerald is a green stone, formula Be 3 Al 2 (SiO 3) 6. According to biblical legend, the blood of Christ was collected in an emerald cup. The Roman Emperor Nero watched Rome burn through an emerald monocle. Determine the mass fraction of all elements in this compound.
Problem 2. a) Turquoise has a blue color due to the presence of copper ions in this compound. It is chemically unstable: it absorbs moisture, absorbs fats, is “afraid” of the sun, interacts with carbon dioxide, acquiring a green color. A pebble weighing 208 g contains 16 g of copper atoms. Calculate the mass fraction of copper in turquoise.
b) Ruby, which in Ancient India was called the king of precious stones, is a type of the mineral corundum (Al 2 O 3). Its red color is caused by impurities of Chromium atoms. A ruby crystal weighing 167g contains 15g of Chromium atoms. Calculate the mass fraction of Chromium in this crystal.
2. Calculation of the mass ratio of elements in a complex substance using its formula
Algorithm
1.Write down an abbreviated condition of the problem.
2.Write a formula for calculating the mass ratios of elements, indicating their symbols in brackets:
m (A) : m (B) : m (C) = xM(A) : yM(B) : zM(C)
4.Write down the answer.
Task 1. Find the mass ratio of elements in aluminum sulfate Al 2 (SO 4) 3.
Task 2. Find the mass ratio of elements in glucose C 12 H 22 O 11
3. Calculation of the mass of an element from a known mass fraction.
Algorithm
1. Write down an abbreviated condition of the problem
2. Determine the relative molecular mass of a given substance
3. Determine the mass of the element using the formula
m(E) = W m(v)
4. Write down the answer
Task 1. Hematite is a semi-precious stone from black to red, known in Ancient Egypt. The mass fraction of Iron in it is 0.7. Calculate the mass of Iron in a pebble weighing 50 g.
Task 2. A) The mineral sylvite, which has the chemical formula KCl, is used as a potassium fertilizer. Calculate the mass of potassium atoms contained in 50 g of sylvite.
B) Rock crystal is crystalline, transparent, colorless quartz with the chemical formula SiO 2. In ancient Greece it was believed that this was petrified crystal water that had completely lost its heat. What mass of Silicon is contained in a rock crystal crystal weighing 200 g?
4. Calculation of the mass of a substance based on the known mass fraction of the element.
Algorithm 1. Write a shortened condition of the problem
2. Determine the relative molecular or formula mass of a substance
3.Knowing the mass fraction of the element and its mass in the substance, using the proportion we find the mass of the compound.
4.Write down the answer.
Task 1. Blue sapphires have long been “royal stones” - symbols of wisdom, power, and victory. This is a type of corundum with a mass fraction of Aluminum of 52.9% and impurities of Titanium and Iron. Calculate the mass of a sapphire crystal containing 5.4 g of aluminum atoms.
Problem 2. Marble, limestone, calcite and chalk are varieties of a compound with the chemical formula CaCO 3. Determine what mass of this compound contains 120 g of carbon atoms.
5. Finding formulas of substances based on data on the mass fractions of elements.
Algorithm
1. We briefly write down the conditions of the problem.
2. Determine the relative molecular or formula mass
of this substance.
3. Using the formula n=W Mr/Ar 100%, you can determine the number of atoms of each element in the formula.
4. Write down the answer.
Task 1. The mineral pyrite is an ore from which iron is obtained. It contains 47% iron and 53% sulfur. The relative formula mass of pyrite is 120. Determine the formula of pyrite.
Task 2. Determine the formula of hematite - a compound of iron with oxygen, in which the mass fraction of iron is 70%.
6. Finding the formula of a substance from the mass ratios of elements.
Algorithm
We write down a brief statement of the problem.
Write down a formula for calculating the mass ratios of elements, indicating their symbols in brackets:
m (A) : m (B) : m (C) = X: Y: Z,
Go to mass ratios that would contain a whole number of atoms of each type.
Write down the formula of the substance.
Task 1. Establish the simplest formula of a substance, which contains hydrogen, carbon, oxygen and nitrogen in mass ratios of 1: 3: 4: 7.
Task 2. The mass ratios of copper, sulfur and oxygen are 2:1:2. Derive the formula of the substance.
Independent work.
1. Calculate the mass fraction of copper in the CuSO 4 compound
A) 20; B) 40; B) 60; D) 80
2. The mass fraction of sodium in soda is 27%. Calculate mass
sodium atoms in soda weighing 20 g.
A)6.8; B)8.2; B) 5.4; D)3.6
A) 249; B)124.5; B)150.9; D)265.8
4. Derive the formula of pyrolusite if it is known that its composition includes manganese and oxygen with mass fractions of 63% and 37%, and the relative formula mass is 87.
A)MnO; B) MnO 2; C) Mn 2 O 3; D) Mn 2 O 7
A)22, B)33, C)44, D) 66
2. The mass fraction of iron in siderite is 48%. Calculate the mass of iron atoms in a mineral weighing 200 g.
A)67.5; B)56.8; B)62.5; D)34.8
4. Establish the formula of cinnabar if it is known that it contains mercury and sulfur with mass fractions of 86% and 14%, and the relative formula mass is 233.
A) HgS; Hg 2 S HgS 2 Hg 2 S 3
Teacher. Each substance has its own, only characteristic chemical formula, which shows the qualitative and quantitative composition. Using the formula, you can give a name to the substance. In addition, the formula is used to find its relative formula mass and the mass fraction of elements in the compound. To describe a substance using a formula, you can use the following plan.
Qualitative composition of a substance (elements that form it).
Complex or simple substance.
Quantitative composition (the number of atoms of each element in a formula unit).
The relationships between atoms of different elements in a substance.
Relative formula weight.
Mass fraction of elements in a compound.
Here we are at the pinnacle of knowledge. Today, each of you won your own small victory. Let's put our flags on the level of knowledge that we have achieved in the lesson.
V.Homework
Learning is a job that begins at school and ends at home.
Repeat §10
Complete the task using the cards
Find and prepare interesting information for a presentation about precious stones (legends, historical facts, effects on health, fate, talismans)
LESSON TOPIC: Mass fraction of a chemical element in a compound.
THE PURPOSE OF THE LESSON: Learn to calculate the mass fraction of elements in a compound using the formula of the compound and establish the chemical formula of a complex substance using the known mass fractions of chemical elements.
Basic concepts. Mass fraction of a chemical element.
Planned learning outcomes
Subject. Be able to calculate the mass fraction of an element in a compound using its formula and establish the chemical formula of a complex substance using the known mass fractions of chemical elements.
Metasubject . Develop the ability to establish analogies and use algorithms to solve educational and cognitive problems.
Main types of student activities. Calculate the mass fraction of an element in a compound using its formula. Establish the chemical formula of a complex substance using known mass fractions of chemical elements.
Lesson structure
I. Organizational stage
II. Updating of reference knowledge
III. Learning new material
IV. Consolidation. Summing up the lesson
V. Homework
During the classes
Organizing time.
Checking homework.
Updating basic knowledge.
Give definitions: relative atomic mass, relative molecular mass.
In what units can relative atomic mass be measured?
In what units can relative molecular mass be measured?
Learning new material.
Working with the textbook. Workbook.
Guys, let's say we have a substance - sulfuric acidH 2 SO 4,
Can we find out which atoms are part of the compound?
And their number?
And in what mass ratio do they combine?
Calculation of chemical mass ratios
elements in a complex substance. (page 51)
How can you find out in what mass ratios the elements are combined in a compound whose formula isH 2 SO 4 ?
m(H): m(S): m(O)= 2*2 + 32 + 16*4= 2:32:64 = 1:16:32.
1+16+32 = 49, that is, 49 parts by mass of sulfuric acid, contains 1 part by mass of hydrogen, 16 parts by mass of sulfur, 32 parts by mass of oxygen.
Guys, what do you think, can we calculate the proportion of each element in the compound?
Today we will get acquainted with the new concept of mass fraction of an element in a compound.
W- mass fraction of the element in the compound.
n- number of atoms of the element.
Mr- relative molecular weight.
Calculation of mass fractions of chemical elements
in a complex substance. (RT)
1. Study the algorithm for calculating the mass fraction of an element in a compound.
Task No. 1 (RT)
Deriving chemical formulas if the mass fractions of chemical elements are known,
included in this substance. (RT)
2. Study the algorithm for calculating the mass fraction of an element in a compound.
Problem No. 5 (RT)
Consolidation of the studied material.
RT page 25 No. 2.
RT page 27 No. 6.
Summing up the lesson.
What new concepts did you learn in class today?
Independent work.
Homework:
study §15 pp. 51 - 53;
answer questions No. 3,4,7 pp. 53-54 (in writing).
P List of used literature.
Textbook. Chemistry 8th grade. auto G.E. Rudzitis, F.G. Feldman. Publishing house "Prosveshcheniye", 2014.
Chemistry workbook. auto Borovskikh T.A.
