Knowing the chemical formula, you can calculate the mass fraction of chemical elements in a substance. element in substance is denoted in Greek. letter “omega” - ω E/V and is calculated using the formula:
where k is the number of atoms of this element in the molecule.
What is the mass fraction of hydrogen and oxygen in water (H 2 O)?
Solution:
M r (H 2 O) = 2*A r (H) + 1*A r (O) = 2*1 + 1* 16 = 18
2) Calculate the mass fraction of hydrogen in water:
3) Calculate the mass fraction of oxygen in water. Since water contains atoms of only two chemical elements, the mass fraction of oxygen will be equal to:
Rice. 1. Formulation of the solution to problem 1
Calculate the mass fraction of elements in the substance H 3 PO 4.
1) Calculate the relative molecular mass of the substance:
M r (H 3 PO 4) = 3*A r (N) + 1*A r (P) + 4*A r (O) = 3*1 + 1* 31 +4*16 = 98
2) Calculate the mass fraction of hydrogen in the substance:
3) Calculate the mass fraction of phosphorus in the substance:
4) Calculate the mass fraction of oxygen in the substance:
1. Collection of problems and exercises in chemistry: 8th grade: to the textbook by P.A. Orzhekovsky and others. “Chemistry, 8th grade” / P.A. Orzhekovsky, N.A. Titov, F.F. Hegel. - M.: AST: Astrel, 2006.
2. Ushakova O.V. Chemistry workbook: 8th grade: to the textbook by P.A. Orzhekovsky and others. “Chemistry. 8th grade” / O.V. Ushakova, P.I. Bespalov, P.A. Orzhekovsky; under. ed. prof. P.A. Orzhekovsky - M.: AST: Astrel: Profizdat, 2006. (p. 34-36)
3. Chemistry: 8th grade: textbook. for general education institutions / P.A. Orzhekovsky, L.M. Meshcheryakova, L.S. Pontak. M.: AST: Astrel, 2005.(§15)
4. Encyclopedia for children. Volume 17. Chemistry / Chapter. ed.V.A. Volodin, Ved. scientific ed. I. Leenson. - M.: Avanta+, 2003.
1. Unified collection of digital educational resources ().
2. Electronic version of the journal “Chemistry and Life” ().
4. Video lesson on the topic “Mass fraction of a chemical element in a substance” ().
Homework
1. p.78 No. 2 from the textbook “Chemistry: 8th grade” (P.A. Orzhekovsky, L.M. Meshcheryakova, L.S. Pontak. M.: AST: Astrel, 2005).
2. With. 34-36 No. 3.5 from the Workbook in Chemistry: 8th grade: to the textbook by P.A. Orzhekovsky and others. “Chemistry. 8th grade” / O.V. Ushakova, P.I. Bespalov, P.A. Orzhekovsky; under. ed. prof. P.A. Orzhekovsky - M.: AST: Astrel: Profizdat, 2006.
Summary of a chemistry lesson in 8th grade. Topic "Mass fraction"
"mass fraction 8th grade"
Integrated lesson chemistry + mathematics on the topic:
“Mass fraction of an element in a compound”, grade 8
(intensive learning technology, ICT)
The purpose of the lesson: consider an algorithm for solving problems of finding the mass fraction of an element in a molecule and deriving the chemical formula of a substance. To introduce techniques for solving problems in mathematics and chemistry, to expand knowledge about the meaning of the mass fraction of an element in a molecule, to form a holistic picture of the relationship between subjects at school.
Tasks:
Educational:
1. Formation of the concept of the mass fraction of an element in the composition of a substance.
2. Application of knowledge about the mass fraction of an element in the composition of a substance in everyday life.
3. Solving problems with finding the mass fraction of an element in the composition of a substance.
Educational:
1. Develop the ability to independently choose a method for solving problems.
2. The ability to generalize, abstract and concretize knowledge.
3.Development of a scientific worldview, creative thinking through the creation of a problem situation.
Metasubject:
Contribute to the formation of skills to analyze, compare, and generalize knowledge;
Continue to develop the ability to work in a team;
Cultivate respect for the opinions of other team members and staff;
Develop a sense of responsibility for your work.
Personal:
Form a conscious need for knowledge;
Develop the ability to manage your learning activities;
Equipment:
1. Chemical reagents and utensils.
2. Interactive whiteboard.
3. Supporting notes.
4. Cards.
Lesson type: combined lesson.
(Intensive concept building training)
Teaching methods: partially search, reproductive, verbal – visual – practical.
Teacher's activities:
Plans students’ work in advance, exercises operational control, provides assistance, support and makes adjustments to their activities.
During the classes.
Stage. Organizing time.
greeting students and guests.
Determining the topic of the lesson, the goals of the lesson: formulas of simple and complex substances are posted on the board, Sn, Cl 2 O 7, C, Mn 2 O 7, Pb, H 2 SO 3, Ag , AgNO 3 .
(what do we see on the board?
On what basis can they be divided?
What is called a simple (complex) substance?
What physical quantities can we use for these formulas?
And so the topic of our lesson?.......
Stage. Updating knowledge. Reception: tAik of – touch down (stand up – sit down)
Is the relative atomic mass of an element indicated for each element in the PSHE? (Yes)
The absolute mass of an atom is equal to the product of the relative atomic mass and 1/12 of the mass of the carbon atom? (Yes)
79.932≈80? (Yes)
– a quantity equal to the sum of all relative atomic masses and is dimensionless Mr = ∑ Аr × N ? (Yes)
Mr(NaCl)=23+36=59 ? ( No )
Does each atom have a relative atomic mass? (Yes)
Is a percentage 1/100 of a number? (Yes)
Relative atomic mass of an element - a value equal to the ratio of the mass of an atom of an element to ½ the mass of a carbon atom? (No)
17%=0.017? (No)
(Ar ) ? (Yes)
III stage. Independent work.
| formula | m ; G |
|||
| 1.97*10 -25 kg |
||||
| Sa 3 (P.O. 4 ) 2 |
| formula | m ; G |
|||
| 1.99*10 -26 kg |
||||
| CO 2 |
| formula | m ; G |
|||
| 3.43*10 -25 kg |
||||
| H 2 SO 3 |
| formula | m ; G |
|||
| 1.79 *10 -25 kg |
||||
| AgNO 3 |
Checking independent work. Reception: Coners "Angles".
Participants No. 1 in the 1st corner
Participants No. 2 in the 2nd corner
Participants No. 3 to the 3rd corner
Participants No. 4 to the 4th corner
IV stage. Physical exercise. Formation into teams. Reception:Mix - Freeze - Group . Mix-Freeze-Group. “Mix-freeze-group” (MSHE)
1. How many A-elements are in the 1st group of PSHE? (6)
2. What is the total number of atoms in a water molecule? (3)
3. Find a number if 25% of it is equal to 2? (8)
4. How many groups of chemical elements are there in PSCE? (8)
5. In what period of PSCE is the U atom located? (7)
6. How many kilograms make up 5% of a hundredweight? (5kg)
6. Relative atomic mass Ne? (4)
V stage. Learning new material
Chemistry teacher: Guys, let's go back to the formulas on the board. Reading the CO 2 molecule. What is she showing us?
show the number of atoms of each type.
We will also compare the substance in question with the CO molecule - carbon monoxide. How do these chemical formulas differ?
Mathematic teacher: and from a mathematical point of view, different percentages of atoms in a molecule. To make this clear, let us remember:
1) What is a share? (part of the number)
2) How can it be expressed? (fraction)
3) What other concept gives us an idea of a part of a number? (percent)
4) How to find a number if you know what percentage it is of the whole? (divide the integer by 100 and multiply by the number %)
5) Based on the calculations you did in your independent work, what is the relative molecular weight of a carbon dioxide (CO 2) molecule? (Mr =12+16*2=44)
6) Find the part of the relative molecular mass of the proposed molecule for carbon, knowing its relative atomic mass and the number of atoms in the molecule. (Ar(C)=12*1=12)
7) What is the ratio of the relative atomic mass of an element to the relative molecular mass? (12/44=3/11=0, (27)) Express the fraction as a percentage. Thus we expressed the share.
Chemistry teacher:
What physical quantity did you work with when expressing a fraction? (weight)
Does this mean that we have found the mass fraction of the element in the molecule?
Let's compare the resulting formula with the proposed formula on page 42.
Using the formula, find the mass fraction of oxygen combined with carbon?
(16*2/44= 32/44=8/11= 0, (72) =73%.
Draw a conclusion.
VI stage. Consolidation of the studied material. Receptionrelly table
Shoulder neighbors. Problem 1: “Calculate the mass fraction of hydrogen, sulfur and oxygen in sulfurous acid whose formula is H 2 SO 3
Problem 2:
Calculate the mass fraction of calcium, phosphorus, oxygen in phosphate rock and chlorine, the formula of which is Ca 3 (P.O. 4 ) 2
Given: Solution:
Sa 3 (P.O. 4 ) 2 M r (Sa 3 (P.O. 4 ) 2 )= 40×4 (31+16×4)×2=310
w (P) -? w Ca= 40×3/ 310 = 0.387, or 38,7%
w(O)-? w O = (16×4)×2/ 310 = 0.413, or 41.3%
w (WITHa ) -? w P = 31×2/310= 0.2, or 20%
w (total)=38.7+41.3+20=100%
VII stage. Reflection.
Importance of knowledge about mass fraction
You can determine the content of an element in any mass of a substance.
In the national economy, determine the content of a nutrient in a certain substance
VIII stage. Admission: exit ticket.
800 Rubles Samari. Presentation for 800 rubles
4. What is the importance of knowing the mass fraction..., for example, adding superphosphate (nutrient salt) to the soil.
Lesson grades.
View document contents
"formulas"
Cl 2 O 7
Mn 2 O 7
H 2 SO 3
AgNO 3
CO 2
View document contents
"Handout material"
| Name of quantities | Designation | Units | Entry form | Mathematical expression |
|
| Mass of substance | m | M(CaO) = 56 g. | m= M× ν |
||
| Quantity of substance | ν ( n) | ν(KCl) = 0.1 mol | ν = N / N A |
||
| Avogadro's constant | N A | N A = 6.02 ×10 23 mol -1 | N A = N / ν |
||
| Molar mass | M | g/mol, kg/mol | M (HCl) =36.5 g/mol M (HCl) =36500 kg/mol | M=n /ν |
|
| V m | V m =(O 2)=22.4 l/mol | V m =V / ν |
|||
| Volume of gaseous substance (or solution) | V | V (CO 2 ) = 5.6 l | V = V m × ν |
||
| Relative atomic mass | Ar | Dimensionless | Ar(Ca)=40 | Ar= |
|
| Relative molecular weight | Mr | Dimensionless | Mr(H2O) = 18 | Ar= |
|
| Density | P | P(H 2 O)=1g/ml | P=m / V |
| Name of quantities | Designation | Units | Entry form | Mathematical expression |
|
| Mass of substance | m | M(CaO) = 56 g. | m= M× ν |
||
| Quantity of substance | ν ( n) | ν(KCl) = 0.1 mol | ν = N / N A |
||
| Avogadro's constant | N A | N A = 6.02 ×10 23 mol -1 | N A = N / ν |
||
| Molar mass | M | g/mol, kg/mol | M (HCl) =36.5 g/mol M (HCl) =36500 kg/mol | M=n /ν |
|
| Molar volume of gas (at normal conditions) | V m | V m =(O 2)=22.4 l/mol V m =(O 2)=22.4×10 -3 kg/mol | V m =V / ν |
||
| Volume of gaseous substance (or solution) | V | V (CO 2 ) = 5.6 l | V = V m × ν |
||
| Relative atomic mass | Ar | Dimensionless | Ar(Ca)=40 | Ar= |
|
| Relative molecular weight | Mr | Dimensionless | Mr(H2O) = 18 | Ar= |
|
| Density | P | P(H 2 O)=1g/ml | P=m / V |
| formula | Ar | Mr | m ; G |
|
| Sa 3 (P.O. 4 ) 2 |
| formula | Ar | Mr | m ; G |
|
| CO 2 |
| formula | Ar | Mr | m ; G |
|
| H 2 SO 3 |
| formula | Ar | Mr | m ; G |
|
| Ag | ||||
| AgNO 3 |
| formula | Ar | Mr | m ; G |
|
| Sa 3 (P.O. 4 ) 2 |
| formula | Ar | Mr | m ; G |
|
| CO 2 |
| formula | Ar | Mr | m ; G |
|
| H 2 SO 3 |
| formula | Ar | Mr | m ; G |
|
| Ag | ||||
| AgNO 3 |
| formula | Ar | Mr | m ; G |
|
| Sa 3 (P.O. 4 ) 2 |
| formula | Ar | Mr | m ; G |
|
| CO 2 |
| formula | Ar | Mr | m ; G |
|
| H 2 SO 3 |
| formula | Ar | Mr | m ; G |
|
| Ag | ||||
| AgNO 3 |
| formula | Ar | Mr | m ; G |
|
| Sa 3 (P.O. 4 ) 2 |
| formula | Ar | Mr | m ; G |
|
| CO 2 |
| formula | Ar | Mr | m ; G |
|
| H 2 SO 3 |
| formula | Ar | Mr | m ; G |
|
| Ag | ||||
| AgNO 3 |
| formula | Ar | Mr | m ; G |
|
| Cl 2 O 7 |
| formula | Ar | Mr | m ; G |
|
| CO 2 |
| formula | Ar | Mr | m ; G |
|
| H 2 SO 3 |
| formula | Ar | Mr | m ; G |
|
| Ag | ||||
| AgNO 3 |
| formula | Ar | Mr | m ; G |
|
| Cl 2 O 7 |
| formula | Ar | Mr | m ; G |
|
| CO 2 |
| formula | Ar | Mr | m ; G |
|
| H 2 SO 3 |
| formula | Ar | Mr | m ; G |
|
| Ag | ||||
| AgNO 3 |
View presentation content
"mass fraction 8kl presentation"
Cl 2 O 7
Mn 2 O 7
H 2 SO 3
AgNO 3
take-off - touch down
stand up - sit down
RECALL
- Does each atom have a relative atomic mass?
- Is a percentage 1/100 of a number?
- Relative atomic mass of an element - a value equal to the ratio of the mass of an atom of an element to ½ the mass of a carbon atom?
- 17%=0,017?
- The relative atomic mass of an element is denoted ( Ar ) ?
- 25%=1/4? (Yes)
take-off - touch down
stand up - sit down
RECALL
- Is the relative atomic mass of an element indicated for each element in the PSHE?
- The absolute mass of an atom is equal to the product of the relative atomic mass and 1/12 of the mass of the carbon atom?
- 79,932≈80?
- Relative molecular mass is a value equal to the sum of all relative atomic masses and is dimensionless
- Mr = ∑ Аr × N ?
- Mr(NaCl)=23+36=59 ?
ON ONE'S OWN
formula
m ; G
During the execution of the structure, participants are distributed in different corners...
Participants No. 1 in the 1st corner
Participants No. 2 in the 2nd corner
Participants No. 3 to the 3rd corner
Participants No. 4 to the 4th corner
for further presentation of their point of view and acceptance of the points of view of their partners.
Mix-Freeze-Group
Mix-Freeze-Group
"Mix-freeze-group"
1. How many A-elements are in the 1st group of PSHE?
2. What is the total number of atoms in a water molecule?
3. How many groups of chemical elements are there in PSCE?
4. In what period of PSCE is the U atom located?
5. Relative atomic mass Ne?
CHEMICAL FORMULA
- this is a conventional notation of the composition of a substance using chemical symbols and indices
chemical sign
carbon
chemical sign
oxygen
- Qualitative composition (what atoms);
- Quantitative composition (how many atoms);
- Relative molecular weight;
- Whether a substance belongs to a number of simple or complex substances;
- The relative abundance of an element in a sample of a substance.
indices
show the number of atoms of each type
- What is a share?
- How can it be expressed?
- What other concept gives us an idea of a part of a number?
- How to find a number if you know what percentage of the whole it is?
- Based on the calculations you did in your homework, what is the relative molecular weight of a carbon dioxide (CO2) molecule?
- Find the part of the relative molecular mass of the proposed molecule for carbon, knowing its relative atomic mass and the number of atoms in the molecule?
- What is the ratio of the relative atomic mass of an element to the relative molecular mass? Express the fraction as a percentage.
PROBLEM SOLVING
Determine the mass fraction of aluminum in its combination with oxygen Al 2 O 3
Given: Solution:
CO 2 w c = A r (C)/M r (CO 2 )
M r (CO 2 )= 12+ 16×2=44
w c = 12 / 44 = 0.27 or 27%
Answer: mass fraction O 27%
w(Al) = ?
MASS FRACTION OF AN ELEMENT IN THE COMPOUND (w)
is the ratio of the mass of all atoms of an element to the relative molecular mass of the substance.
ON ONE'S OWN:
Calculate the mass fraction of oxygen in the same compound.
Examination
w ABOUT = 16×2 / 44 = 0.72 or 72%
ANSWER: mass fraction O=72%
The sum of the mass fractions of all chemical elements in a compound is ≈ 1 or ≈ 100%.
w C +w ABOUT = 27% + 72% = 99 %
RELLY TABLE
“RECORDING SHORT ANSWERS IN TURN IN PAIRS”
NEIGHBORS ON THE SHOULDER
Task 1: Calculate the mass fraction of hydrogen, sulfur and oxygen in sulfurous acid whose formula is H 2 SO 3
Task 2: Sa 3 ( P.O. 4 ) 2
RELLY TABLE
“RECORDING SHORT ANSWERS IN TURN IN PAIRS”
Calculate the mass fraction of hydrogen, sulfur and oxygen in sulfurous acid whose formula is H 2 SO 3
Given: Solution:
H2SO3 w H = A r (H)/M r (H 2 SO 3 )
w S = A r (S)/M r (H 2 SO 3 )
w S = A r (O)/M r (H 2 SO 3 )
W(H) -? M r (H 2 SO 3 )= 1*2+32+16*3=82
W(S)-? w H = 1*2 / 82 = 0.024, or 2.4%
W(O)-? w S = 32/ 82 = 0.39, or 39%
w O = 16*3/ 82 = 0.585, or 58.5%
w (total)=2.4+39+58.5=99.9%
Answer: mass fraction of H – 2.4%; S – 39%; O – 58.5%
RELLY TABLE
“RECORDING SHORT ANSWERS IN TURN IN PAIRS”
Calculate the mass fraction of calcium, phosphorus, oxygen in phosphate rock, the formula of which is Sa 3 ( P.O. 4 ) 2
Given: Solution:
Sa 3 ( P.O. 4 ) 2 M r ( Sa 3 ( P.O. 4 ) 2 )= 40×4 (31+16×4)×2=310
w (P) -? w Ca = 40×3/ 310 = 0.387, or 38.7%
w(O)-? w O = (16×4)×2/ 310 = 0.413, or 41.3%
w(Ca) -? w P = 31×2/310= 0.2, or 20%
w (total)=38.7+41.3+20=100%
Answer: mass fraction of Ca – 38.7%; P– 20%; O – .41.3%
- You can determine the content of an element in any amount of a substance
- You can determine the chemical formula of a substance;
- In the national economy, determine the content of a nutrient in a certain substance
800 Rubles Samari
Presentation for 800 rubles
1. What is called a chemical formula?
2. What does the chemical formula show?
3. What is the mass fraction expressed in?
4. What is the importance of knowledge about the mass fraction...
For example, adding superphosphate (nutrient salt) to the soil
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.
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.
