Lesson objectives:
1) to form students' knowledge about the rate of a chemical reaction, about the factors affecting the rate of a chemical reaction;
2) to show its significance in nature and human activity;
3) deepen knowledge about catalysts.
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Lesson on the topic "The rate of a chemical reaction" (Grade 9).
Lesson objectives:
1) to form students' knowledge about the rate of a chemical reaction, about the factors affecting the rate of a chemical reaction;
2) to show its significance in nature and human activity;
3) deepen knowledge about catalysts.
Planned learning outcomes:
Subject: students have an idea about the rate of a chemical reaction, about the units of its measurement, they know the influence of various factors on the rate of a chemical reaction (the nature of the reactants, their concentration, contact area and temperature).
Metasubject: group work skills are formed, independence of thinking develops, the ability to generalize, analyze and highlight the main thing.
Personal: develop communication skills in the course of group work, the ability to apply the acquired knowledge in practice, students realize the meaning and value of knowledge.
Basic concepts of the lesson:the rate of a chemical reaction, factors affecting the rate of a chemical reaction.
The main activities of students:independent work with information, group work, work in pairs, observation of chemical transformations, description of chemical reactions, participation in a joint discussion of the results of experiments, generalize and draw conclusions.
Lesson type: lesson learning new material
Study methods:explanatory and illustrative, partially exploratory, research.
Equipment:
Device for determining the rate of a chemical reaction, 10% and 30% solution of HCl, Zn, CuO, H 2 SO 4 solution, Mg, Cu, CaCO 3 chalk, CaCO 3 powder, H 2 O 2, MnO 2, NH 3, (NH 4) 2 Cr 2 O 7, flask 500 ml, spirit lamp.
Epigraph to the lesson
"Knowledge, not verified by experience - the mother of all certainty, is fruitless and full of errors"
Leonardo da Vinci.
Stage I - Actualization of basic knowledge(heuristic conversation with students)
We live in a dynamic world. Objects of animate and inanimate nature move at different speeds. When you studied physics, you learned that man invented supersonic aircraft. In biology lessons, we learned that the amoeba also moves at a certain speed of 0.2 mm per minute, and the fastest wild cat, the cheetah, develops a speed of 60 km per hour. In chemistry lessons, we say that some reactions are fast, others are slow, i.e. reactions also go at a certain speed. How much new information we get, but what do we know about the rate of a chemical reaction? Almost nothing. Therefore, I suggest that you familiarize yourself with this "concept".
Stage II - Studying new material.
Teacher: in physics lessons you have already consideredthe speed of mechanical movement, the movement of the body in space.
How is it designated? What is the formula for calculating the speed of a moving body?
υ = S/t km/h (m/s). This is the distance traveled for a certain period of time.
Teacher: what physical quantity is changing here? (distance from point A to point B). body coordinates. Seeds thrown into the ground germinate in different ways. Some grow quickly, others slowly, but the stalk of the seedling invariably lengthens, the size of the leaves increases.
So speed is the change in some physical quantity per unit of time. In chemistry there is such a thing as the rate of a chemical reaction. What is the rate of a chemical reaction and how is it measured? What physical quantity can change in a chemical reaction over a certain period of time?
Let's take a specific reaction:
2 SO 2 + O 2 \u003d 2 SO 3
What do the coefficients in front of the formulas show?
Pupils: The coefficients show the number of atoms and molecules i.e. amount of substance.
Teacher: Do you think the amount of a substance changes during a chemical reaction?
We took 2 mol SO 2, + 1 mol O 2 , and got 2 mol SO 3 - reaction product.
3 mol of starting material
The number of moles of the starting substances and the product of the reaction are different.
What is the amount of a substance per unit volume called? (Because gaseous substances are involved in the reaction, the coefficients show the volume ratios of gases).
The amount of a substance per unit volume is the concentration (molar concentration), denoted by the letter "C", the unit of measurement is mol / l(Hang a poster on the board.)
The change is denoted by the Greek letter Δ (delta). With 1 - concentration of initial substances, С 2 - concentration of reaction products.
ΔC \u003d C 1 - C 2
(the concentration of the starting substances is greater than the concentration of the reaction products).
The change in molar concentration occurs over a certain period of time.
slide 3
Teacher: Try to define the rate of a chemical reaction and derive a formula for the rate of a chemical reaction, write in the same way as the one written on the board υ \u003d S / t
V \u003d ΔС / Δt \u003d C 1 - C 2 mol / (l.s)
T2-t1
Textbook example p.39
V \u003d (2 - 0.5) : 50 \u003d 1.5: 50 \u003d 0.03 mol / (l.s)
Fixing:
N 2 + 3H 2 → 2NH 3
V 1 v 2 v 3 v 4
t(sec) 0 79 158 316 632
(Students work in groups)
V1 \u003d (1.85-1.67) / (79 - 0) \u003d 0.0023 mol / hp x 10 3 = 2,3
V2 \u003d (1.67-1.52) / (158-79) \u003d 0.0019 mol / hp x 10 3 = 1,9
V3 \u003d (1.52-1.30) / (316-158) \u003d 0.0014 mol / hp x 10 3 =1,4
V4 \u003d (1.30-1.00) / (632-316) \u003d 0.0009 mol / hp x 10 3 = 0,9
Conclusion: The rate of a chemical reaction decreases over time.
Ammonia is used to produce nitrogen fertilizers. Slowing down this process is unprofitable in practice, production will be unprofitable. Can you change the rate of a chemical reaction? If possible, how?
We need to find out what factors affect the rate of a chemical reaction?
Group work.
Exercise 1.
Conclusion: The rate of a chemical reaction depends on the concentration of reactants. (Entry in a notebook).
On the basis of vast experimental material, the "law of mass action" was derived, which reflects the dependence of the rate of a chemical reaction on the concentration of reacting substances.
The rate of a chemical reaction is directly proportional to the product of the concentrations of the reactants. A+B=D
V = k* C A * C B
V \u003d k * [A] * [V]
k - the rate constant of a chemical reaction, numerically equal to the rate of a chemical reaction at a concentration of reactants of 1 mol / l.
Task. Determine how the rate of the chemical reaction of ammonia synthesis changes:
N 2 + 3H 2 → ← 2NH 3
with an increase in the concentration of the starting substances by 2 times:
V 1 = k [ N 2 ][ H 2 ] 3 V 2 = k [ 2H 2 ] 3
[ N 2 ] \u003d x [ H 2 ] \u003d y V 2 \u003d k 2x (2y) 3 \u003d 2 x 2 3 \u003d 16
V 1 k xy 3
Teacher: Concentration affects the rate of a chemical reaction if it involves gases or liquids. Why does concentration not affect the rate of a chemical reaction involving solids?
Teacher: The concentration of solids does not change, unlike gases or liquids. Solids do not compress, there are no gaps between the particles of a solid.
The concentration of gases varies with pressure. When the pressure increases, the concentration increases, when the pressure decreases, it decreases.
Conclusion 2. The rate of a chemical reaction is affected by pressure if gases or liquids are involved in this reaction.
Task. Determine how the rate of a chemical reaction will change
2 SO 2 + O 2 → 2 SO 3
doubling the pressure?
V 1 \u003d k 2 [O 2]; V 2 \u003d k 2 [ 2O 2 ]
[SO 2 ] = x; [O 2] \u003d y V 2 \u003d k (2x) 2 (2y) \u003d 2 2 x 2 \u003d 8 times
V 1 k x 2 y
Group 2 What else can affect the rate of a chemical reaction? (t temperature). Consider the effect of t (temperature) on the rate of a chemical reaction.
Exercise.
Conclusion: The rate of a chemical reaction depends on t. Van't Hoff's rule.
With an increase in t for every 10 C 0 (degrees) the reaction rate increases by 2-4 times.
V 2 \u003d V 1 * ɣ (t2-t1) / 10
ɣ- temperature coefficient.
Task. How many times will the rate of a chemical reaction increase with an increase in t from 10 to 60 degrees, ifɣ = 2 (work at the board)!
Why does the rate of a chemical reaction depend on temperature? What do we do with a substance by raising its temperature? We heat, we impart energy, the energy is spent on the destruction of chemical bonds in the initial substances. The movement of molecules and atoms increases, this leads to an increase in "useful collisions", as a result, more reaction products are formed.
Group 3. Influence of the nature of reacting substances on the rate of a chemical reaction.
Exercise.
Mg + 2HCI \u003d MgCI 2 + H 2
Zn + 2HCI \u003d ZnCl 2 + H 2
Cu + HCl →
Conclusion: The rate of a chemical reaction depends on the nature of the reactants.
What do we understand by the chemical nature of the reactants?
Under the chemical nature we understand the composition of substances, the type and strength of the chemical bond.
Group 4. What else can affect the rate of a chemical reaction?
Task: 3
Conclusion. The rate of a chemical reaction is affected by the contact area of the reactants.
Physical education!!!
Arabic parable of the eighteen camels. There once lived in the east a man who bred camels. He worked all his life, and when he grew old, he called his sons to him and said:
“My children! I am old and weak and will soon die. After my death, divide the camels as I tell you. third part. And you, youngest, take a ninth part."
Time passed and the old man died. Then the sons decided to divide the inheritance as their father had bequeathed to them. They drove the herd to a large field, counted, and it turned out that there were only seventeen camels in the herd. And it was impossible to divide them neither by 2, nor by 3, nor by 9! What was to be done - no one knew. The sons began to argue and each offered his own solution. They were already tired of arguing, but did not come to a common decision. At this time, a traveler on his camel was riding by. Hearing shouting and arguing, he asked, "What happened?"
And the sons told about their trouble. The traveler got down from the camel, let it into the herd and said: "Now separate the camels, as the father ordered." And so the camels became eighteen, the eldest son took half, that is, 9, the middle one - a third, that is, 6 camels, and the youngest ninth, that is, 2 camels. And when they divided the herd in this way, one more camel remained in the field, because 9+6+2= 17. And the traveler got on his camel and rode on.
What is the role of the eighteenth camel? And what is the connection of this parable with the theme of our lesson? In confirmation of the fact that the catalyst affects the rate of a chemical reaction, let's listen to the presentation of the fifth group.
Group 5.
2 O 2. 2
MnO 2
2H 2 O 2 → O 2 +2 H 2 O
Teacher Demonstration Experience (Star Rain)
In a chemical flask with a capacity of 500 ml, place the ammonia solution and close the stopper. We heat ammonium dichromate on a spirit lamp, then place it in a flask with ammonia. We observe the "star rain" reaction.
4NH 3 + 5O 2 \u003d 4NO + 6H 2 O (Cr 2 O 3)
So let's summarize our lesson (students remember the definition of the rate of a chemical reaction, the unit of measurement and indicate the factors that affect the rate of a chemical reaction).
Stage III - consolidation.
Task1. Determine how the rate of the chemical reaction 2SO will change 2 + O 2 →2SO 3 when the pressure is increased by 3 times.
Problem 2. What is the temperature coefficient (ɣ) reaction, if with an increase in temperature by 50 degrees, the speed increases by 32 times?.
Stage IV - reflection
I invite you to evaluate your work in class.
- With what mood did you work, are you satisfied with yourself?
- In my opinion (what did you like?)...
- It was hard for me...
- The most interesting thing for me while working at the lesson was ...
Stage V - Homework.
§fourteen
prepare a short report on the factors affecting the rate of chemical reactions in everyday life, in everyday life.
Appendix 1
research card
group number | chemical experiment | What are we seeing? Chemical equations. reactions | findings |
Exercise 1. Hydrochloric acid solution is given in two test tubes. In the first tube 10% HCI solution, in the second tube 30% HCI solution. A granule of zinc was added to each tube. What are we observing? Write the equations of chemical reactions. Draw your own conclusions. | |||
Exercise. Pour 1-2 ml of sulfuric acid solution into a test tube with copper (II) oxide. What are you watching? Then heat the test tube. What changes occur in the test tube? | |||
Exercise. Three test tubes contain a solution of hydrochloric acid. Pour Mg (magnesium) into the first test tube, put a zinc granule into the second, and Cu (copper) into the third granule. What are we seeing? Let's write the equations of chemical reactions. | |||
Exercise: The same amount of CaCO chalk was placed in two test tubes. 3 in the form of a piece and powder, and 1 ml of hydrochloric acid was poured into these tubes. What are you watching? Write an equation for a chemical reaction. | |||
Task: Two test tubes were taken with a 3% solution of hydrogen peroxide N 2 O 2. . The first test tube was heated in the flame of an alcohol lamp. Add manganese dioxide MnO to the test tube without heating 2 . What are we seeing? What in this example affects the rate of a chemical reaction? |
Fixing: Does the rate of a chemical reaction remain constant throughout the entire process or does it change? For a reaction proceeding in accordance with the equation
N 2 + 3H 2 → 2NH 3
experimentally determined the concentration of one of the substances at different time intervals
υ 1 υ 2 υ 3 υ 4
t(sec) 0 79 158 316 632
C (mol/l) 1.85 1.67 1.52 1.30 1.00
How will the rate of this reaction change with time?
Fixing: Does the rate of a chemical reaction remain constant throughout the entire process or does it change? For a reaction proceeding in accordance with the equation
N 2 + 3H 2 → 2NH 3
experimentally determined the concentration of one of the substances at different time intervals
υ 1 υ 2 υ 3 υ 4
t(sec) 0 79 158 316 632
C (mol/l) 1.85 1.67 1.52 1.30 1.00
How will the rate of this reaction change with time?
Plan
-
lesson summary
«
The rate of chemical reactions
»
(9
Class
)
Goals:
a).Didactic.
Expand and deepen knowledge of chemical reactions. Form
concepts of the rate of a chemical reaction, consider the influence of various
factors on the rate of a chemical reaction. Teach students to explain
factors in terms of the internal structure of matter. Proceed
formation, consolidation of the following skills and abilities: design
and planning a response, working with a book
b).Educational.
To continue the formation of the cognizability of the world and its laws, cause-and-effect relationships of natural phenomena and society. Develop a sense of self-control as you work in class. The development of the personality of students, the formation of their humanistic relations and environmentally appropriate behavior in everyday life and in work.
in).Developing the personality of the student.
In order to develop cognitive interest, entertaining
experience videos. In order to develop the student's thinking, it is planned to compare the rates of chemical reactions depending on the factors influencing them, as well as to generalize and systematize the knowledge gained. To develop the ability to work with substances, perform simple chemical experiments, and follow the rules of safety.
Lesson type
:
learning new material.
Equipment
:
rack with test tubes, test tube holder, spirit lamp,
matches, 2 Petri dishes, iron nail, thread, crystallizer with water.
Reagents
:
sodium, potassium, hydrochloric acid, zinc granules, marble, oxide
copper (II), sulfuric acid solution, barium chloride solution, copper sulfate solution (II).
Methods used in the lesson:
1. explanatory and illustrative;
2. problem-search;
3. reproductive;
4. demonstration experiments as a method of experimental teaching of chemistry.
Application of slide presentation and demonstration of video clips of experiments.
learning techniques
: a story with elements of conversation, work in pairs,
discussion, explanation.
The work program is based on the program
Chemistry. Work programs. The subject line of textbooks by G. E. Rudzitis, F. G. Feldman. Grades 8-9 / N. N. Gara. - M.: Enlightenment.
Textbook
R u d s and t and s G. E. Chemistry: 9th grade: textbook. for general education organizations with app. on electronic media (DVD)/ G. E. Rudzitis, F. G. Feldman. - M.: Enlightenment, 2014-208c.
During the classes
I. Organizational stage
(greeting, readiness check
students for class).
II.
Knowledge update
The teacher demonstrates experiment1 - the interaction of iron with a solution of copper sulfate (II); experience 2-interaction of barium chloride with sulfuric acid.
Pupils see that the reaction with barium chloride with sulfuric acid has passed
instantly, while iron and copper sulfate (II) is still unchanged. Teacher
demonstrates a video clip with 2 experiences, and students describe the signs of a reaction.
Frontal conversation
- What did you observe?Students Answers-2
chemical reactionsii.
- Are both reactions practically feasible?Student responses
-Yes.
- How did you know about it?Student responses
-signs of chemical reactions.
- Did we immediately see signs of a reaction in these experiments?Student responses
-No,
1st reaction went faster,
2nd is slower.
What physical quantity changes over time?Students Answers -
speed.
Why do we need to know about the rate of a chemical reaction?Student responses
- to control and manage processes and predict their course.
- What examples from life can you confirm that chemical
Do the reactions proceed at different rates?Students Answers -
iron rusting,
burning gas,
sour milk,
decay, etc..
d.
How is mechanical speed determined?
Students answers - the speed of mechanical movement is calculated according to the formula: ratio of distance to time.
How is the rate of a chemical reaction determined? Pupils find it difficult
reply.
Teacher - how to determine the rate of a chemical reaction, what kind of value it is, what it depends on, you will learn today in the lesson.
III
.
Learning new material
.
Write down the topic of today's lesson:
"The rate of a chemical reaction".
The rate of a chemical reaction-
is the change in the concentration of a reacted or formed substance per unit of time.
The concentration of a substance is often defined as the number of moles per liter.
With 1
- initial concentration
With 2 concentration over time
Factors,
affecting the rate of chemical reactions:
nature of reacting substances;
concentration of reacting substances;
area of contact of reactants;
temperature;
catalyst.
Let's look at each factor in detail by running a demo
experiments.
BUT).
The nature of the reactants
Interaction of sodium, potassium with water. Experiences are shown
demonstratively. Their differences are discussed,
the conclusion that the rate of a reaction depends on the nature of the reactants,
hence from the internal structure of substances. The records are in the form
tables:
Factors
Chemical reaction equations
findings
The nature of the reactants
2Na + 2H2O = 2NaOH + H2
2K + 2H2O = 2KOH + H2
the rate of a reaction depends on the nature of the reactants
B).
Reactant concentration
A video fragment "Combustion of sulfur in oxygen and in air" is shown.
When discussing, they come to the conclusion that the speed is directly proportional to
concentration of substances (for reactions in solutions in the gaseous state), the combustion of substances in pure oxygen is more intense than in air, where the oxygen concentration is 5 times less.
Demonstration experience. Interaction of zinc with dilute and concentrated hydrochloric acid. Students conclude that with a concentrated reaction goes much faster.
concentration of reacting
substances
S+O2=SO2
The rate is directly proportional to the concentration of substances (for reactions in solutions in the gaseous state)
Zn+2HCL=ZnCL2+H2
concentrated acid reacts faster
AT). Contact area of reactants
Laboratory experiment "Interaction of marble (piece, powder) with hydrochloric acid" There is a discussion that with an increase in the surface area of the reactants, the speed increases.
Substance contact area
CaCO3+2HCL=CaCL 2 +H2O+CO2
As the surface area of the reactants increases, the rate of a chemical reaction increases.
G). Temperature
The teacher performs a demonstration experiment "Interaction of copper oxide (II) with sulfuric acid" without heating and with heating
Temperature
CuO+H2SO4=CuSO4+H2O
For every 10 degrees increase in temperature, the rate of chemical reactions increases by 2-4 times.
D). Catalyst
Problem experience : decomposition of hydrogen peroxide in the presence of manganese oxide (IV).
Explanations: Hydrogen peroxide is an unstable compound and gradually decomposes into water and oxygen in the light. The release of gas is noticeable by the release of bubbles. (demonstration by heating peroxide).Why does peroxide decompose in the presence of manganese oxide ( IV )?
Introducing the concept of "catalyst".
A demonstration experiment is underway.
The teacher is doing an experiment with hydrogen peroxide and manganese oxide.
Instruction for the teacher
Reagents: rr H 2 O 2 , МnО 2 , torch, matches.
Pour 2-3 ml of 3% hydrogen peroxide solution into a test tube.
Note that under normal conditions no noticeable decomposition of hydrogen peroxide is observed.
At the tip of a spatula, add some manganese dioxide to the test tube.
Observe the vigorous outgassing and, with the help of a smoldering splinter, verify that the outgassing is oxygen.
Write down the reaction equation for the decomposition of hydrogen peroxide.
What conclusion can be drawn? What happened to hydrogen peroxide?
catalyst A chemical that speeds up a reaction but is not part of the reaction products.
Academicianonce jokingly described what would happen ifall catalysts suddenly disappeared, the essence of the description was that our planet would soon become a lifeless desert, washed by an ocean of weak .
INHIBITORS (from Lat mhibeo - stop, hold back), substances that inhibit chemical reactions.
And now the same experience, but with pieces of raw and boiled potatoes. (The teacher makes an experiment, but does not give an answer). I intend not to explain what happens in this case. I suggest that you find the answer yourself and tell us in the next lesson, filling out your story, presentation in the form of a report on the work done. A research task is given "What happens to hydrogen peroxide when exposed to raw potatoes and boiled?"
- ToDo you think there are catalysts in nature? (Enzymes) (Yes)
What new did you learn in the lesson?
How does the rate of reactions depend on various factors, how to speed up the reaction?
Where can you apply what you have learned in practice? (Deceleration of some chemical processes, acceleration of some processes).
IV . CONSOLIDATION OF KNOWLEDGE. GENERALIZATION AND SYSTEMATIZATION
Group work.
1. The rate of a chemical reaction depends on:
A) on the nature of the reacting substances;
B) on the reaction temperature;
C) from the presence of a catalyst;
D) from each of the listed factors.
2. The rate of interaction of a hydrochloric acid solution is maximum with a piece
iron 3) zinc
magnesium 4) copper
3 . The rate of interaction of a hydrochloric acid solution with zinc will be the highest if zinc is in the form:
1).granules, 3).chips,
2).plates, 4). powder.
4. The rate of interaction of a zinc granule is maximum with an acid solution
1) coal, 3) hydrochloric,
2) acetic, 4) sulphurous.
5. More hydrogen will be released within one minute if the following is used for the reaction:
A).Zn(granules) and CH 3 COOH (10% solution)
B). Zn (powder) and HCl (10% solution)
B). Zn (granules) and HCl (10% solution)
G). Zn(powder) and CH 3 COOH (10% solution)
6. Why are perishable foods stored in the refrigerator?
a). moisture is retained
b) the rate of chemical reactions decreases,
in). taste improves,
G). there is no correct answer.
7. Why do flour mills sometimes explode?
a) flour ignites at low temperatures;
b). flour has a large outer surface area;
c) flour has a low moisture content;
G). there is no correct answer.
8. Indicate the acid in which zinc will dissolve most slowly (the mass fraction of all acids in the solution is 20%):
a) salt;
b) sulfuric;
c) hydroiodic;
d) vinegar.
9. At room temperature, the reaction proceeds at the lowest rate:
a) granulated zinc with 2% H solution 2 SO 4
b) zinc powder with 2% H solution 2 SO 4
c) granulated zinc with 10% H solution 2 SO 4
d) zinc powder with 10% H solution 2 SO 4
v. Reflection
ToThe class is divided into 4 groups.
(The teacher calls groups of 3 factors. If the factor is correct, then the group clap their hands together. For each correct answer - 1 point, for incorrect 0).
1 group : temperature , wind, amount of substances.
2 group : climate, water,concentration of substances .
3 group : volume; for the reactionscatalyst , weight.
4 group : for solids -surface area , nature of substances , electricity.
The rate of a chemical reaction characterizes how quickly or slowly the transformation of substances proceeds. Chemical kinetics is the study of the rates of chemical reactions. One of its most important tasks is to control the reaction rate.
For a homogeneous reaction proceeding in a constant volume, the reaction rate is equal to the change in the concentration of any of the substances participating in the reaction per unit time:
If the concentration decreases (C 2< С 1), то перед дробью ставят знак «минус», т. к. скорость не может иметь отрицательное значение.
1. Nature of the reactants
For example, metals (sodium and potassium) with the same substance - water - react at different rates. Potassium reacts very vigorously with water, and the released hydrogen ignites in air (Fig. 2). Sodium reacts more easily with water (Fig. 1).
Rice. 1. Interaction of sodium with water
Rice. 2. Interaction of potassium with water
2. Concentration of starting substances
The greater the concentration of substances, the greater the likelihood of a collision of the reacting substances, therefore, the greater the rate of the reaction.
3. Temperature
Many chemical processes accelerate with increasing temperature. For example, meat at room temperature will spoil much faster than in the refrigerator; in countries with a humid tropical climate, cars rust faster than in northern latitudes.
For example, if a little black powder of copper (II) oxide is added to a solution of sulfuric acid, no changes will be observed. When the mixture is heated, the solution will turn blue.
4. Pressure
Pressure affects the reaction rate when the reaction proceeds with the participation of gaseous substances. As the pressure increases, the reaction rate increases. This is due to the fact that with increasing pressure, the distance between molecules decreases, therefore, the probability of collisions of molecules leading to the transformation of a substance increases.
5. Surface area of contact of initial substances
The greater the degree of grinding of the solid, the greater the area of contact of the substance with the solution. This, in turn, affects the rate of the reaction. The greater the surface area of contact of the reactants, the greater the rate of the reaction.
6. Presence of a catalyst
The rate of chemical reactions may depend on the presence of certain substances.
Substances that speed up a chemical reaction but are not themselves consumed in it are called catalysts.
If you mix aluminum powder with iodine powder, then there will be no signs of a reaction. The reaction does not go. But as soon as you add a catalyst - a drop of water - a violent reaction begins. Water, in this case, participates in the reaction, accelerating the transformation of substances, but is not itself consumed in it.
Rice. 3. Interaction of aluminum with iodine in the presence of water
It should be remembered that one catalyst can speed up one reaction, but not another. There are also reactions that proceed quickly without a catalyst. Such reactions are called non-catalytic. For example, these are ion exchange reactions in solutions.
Some reactions, under certain conditions, can proceed both in the forward and in the reverse direction. For example, carbon dioxide reacts with water to form carbonic acid, which in turn decomposes into carbon dioxide and water.
CO 2 + H 2 O ↔ H 2 CO 3
Such reactions are written with a sign of reversibility and are called reversible.
If in a reversible reaction the rates of the forward and reverse reactions are equal, then such a state is called chemical equilibrium.
Bibliography
1. Orzhekovsky P.A. Chemistry: 9th grade: textbook for general education. inst. / P.A. Orzhekovsky, L.M. Meshcheryakova, M.M. Shalashova. - M.: Astrel, 2013. (§14)
2. Rudzitis G.E. Chemistry: inorgan. chemistry. Organ. chemistry: textbook. for 9 cells. / G.E. Rudzitis, F.G. Feldman. - M.: Enlightenment, JSC "Moscow Textbooks", 2009. (§14)
3. Khomchenko I.D. Collection of problems and exercises in chemistry for high school. - M.: RIA "New Wave": Publisher Umerenkov, 2008.
4. Encyclopedia for children. Volume 17. Chemistry / Chapter. ed. V.A. Volodin, leading. scientific ed. I. Leenson. - M.: Avanta +, 2003. (p. 116-131)
1. A single collection of digital educational resources (video experiences on the topic) ().
2. Electronic version of the journal "Chemistry and Life" ().
Homework
1. p. 99 Nos. 3-8 from P.A. Orzhekovsky "Chemistry: 9th grade" / P.A. Orzhekovsky, L.M. Meshcheryakova, M.M. Shalashova. - M.: Astrel, 2013.
2. Why do liquid gasoline and ethanol burn quietly, while the vapors of these substances explode when mixed with air?
3. What is a catalyst? How does a catalyst change the rate of a chemical reaction?
I hear - I forget, I see - I remember, I do - I understand.
Lesson topic: The rate of a chemical reaction. Factors affecting the rate of a chemical reaction.
Target: deepen and generalize students' knowledge about the rate of a chemical reaction, about the factors affecting the rate of a chemical reaction;
Tasks:
educational: to form the concept of "the rate of chemical reactions", to derive formulas for calculating the rate of homogeneous and heterogeneous reactions, to consider what factors the rate of chemical reactions depends on;
developing: develop logical thinking: the ability to process and analyze experimental data, establish the relationship between the rate of a chemical reaction and external factors.
educational: educate communicative competencies in the course of teamwork; everyday literacy.
Means of education: multimedia projector, computer, software product, laboratory equipment and reagents;
Teaching methods: reproductive, research, partially search;
Form of organization of classes: conversation, research activity, independent work.
Form of organization of work of students: frontal, individual, group.
Lesson type: assimilation of knowledge based on existing ones.
During the classes:
Justification of the meaning of the topic under study and the purpose of the lesson.
Introductory speech of the teacher: today we have an unusual lesson, in the course of working on today's topic you will make a cluster, the key concept of which will be the topic of our lesson: The rate of a chemical reaction. Factors affecting the rate of a chemical reaction.
We have already got acquainted with the main types of chemical reactions, learned to distinguish them from physical phenomena according to certain characteristics. We made sure that the properties of the substances that entered into the reaction differ from the properties of the formed substances.
It is time to talk about the duration of a chemical reaction, i.e. about the course of a chemical process in the time during which it occurs. Today we will talk about the rate of a chemical reaction, determine the factors that affect the rate of a chemical reaction.
Knowledge update.
What do we know about chemical reactions? (types of reactions that proceed with the release of heat or vice versa when heated; some are fast, some are slow.)
Tell me, have you met in your life with reactions going very quickly?
a) burning; b) soda + vinegar; in)...
How do you determine that they are fast?
What about slow reactions? a) iron rusting; b) sour milk;
information: For the complete decay of a newspaper thrown in the forest - 1 year.
Rusting of a tin can - 10 years.
Glass practically does not break down for centuries.
These reactions are low speed.
Organization of activities for the study of new material.
The rate of a chemical reaction.
From the course of physics, you know the concept of "speed of movement" (work on the table).
| Travel speed | Speed units |
| Train speed: | |
| River flow speed: | |
| Film roll speed: | 24 fps |
| Human oxygen consumption rate: | |
| Speed reaction: |
Question: Remember what is the speed of mechanical movement?
This is the length of the path traveled by the physical body per unit of time.
The ratio of the distance traveled to a unit of time.
Question: What changes in time during mechanical motion?
The coordinates of the body, hence the length of the path.
The film is scrolled through a movie camera at a certain speed - 24 frames per second. What changes over time?
The number of frames.
When breathing, a person consumes oxygen. What changes over time?
The number of liters.
The speed of a process is a change in some physical quantity per unit of time. What changes during a reaction? This is the concentration of the substance.
The study of the rates and mechanisms of chemical reactions is called chemical kinetics.
Consider two examples (the experiment is conducted by the teacher).
On the table are two test tubes, in one is a solution of alkali (KOH), in the other is a nail; add CuSO 4 solution to both test tubes. What are we seeing?
Using examples, students judge the speed of reactions and draw appropriate conclusions.
In the first test tube, the reaction occurred instantly, in the second - there are no visible changes yet.
Let's write the reaction equations (two students write the equations on the blackboard):
CuSO 4 + 2KOH \u003d Cu (OH) 2 + K 2 SO 4; Cu 2+ + 2OH - \u003d Cu (OH) 2
Fe + CuSO 4 \u003d FeSO 4 + Cu; Fe0 + Cu 2+ = Fe 2+ + Cu0
Question: What conclusion can we draw from the reactions carried out?
Question: Why is one reaction instant and the other slow?
To do this, it is necessary to remember that there are chemical reactions that occur throughout the entire volume of the reaction space (in gases or solutions), and there are others that occur only on the contact surface of substances (combustion of a solid in a gas, the interaction of a metal with an acid, a salt of a less active metal ).
Based on the results of the demonstrated experiment, students conclude:
reaction 1 is homogeneous, and reaction 2 is heterogeneous.
The rates of these reactions will be mathematically determined in different ways.
When considering the question of the reaction rate, it is necessary to recall that reactions in chemistry are divided into homogeneous and heterogeneous.
Definition: Reactions that take place in a homogeneous medium (there is no interface between the reactants), for example, in a mixture of gases or in solutions, are called homogeneous (from the Greek homo - “equal”, “same”).
Definition: Heterogeneous are reactions that take place between substances in an inhomogeneous medium (there is an interface between the reacting substances). For example, on the contact surface of a solid and a liquid, a gas and a liquid, a solid and a gas, etc. (from Greek hetero - “different”, “different”).
A) The rate of a chemical reaction for a homogeneous reaction.
Consider the concept of the rate of a chemical reaction for a homogeneous medium.
Question: What is one of the conditions for the implementation of a chemical reaction?
One of the conditions for a chemical reaction is the collision of particles.
What is the relationship between the rate of a chemical reaction and the frequency of particle collisions?
The more particles collide, the faster the rate of a chemical reaction.
Now try to formulate the definition of the rate of a chemical reaction?
The reaction rate is the number of collisions or the number of elementary acts per unit of time.
Since it is not possible to calculate the number of particle collisions, it is necessary to find another value that changes with time during the course of a chemical reaction. The initial substances are converted into reaction products, therefore, the amount of the substance changes.
Conclusion: The rate of a reaction is the change in the concentration of one of the substances that have reacted or formed as a result of the reaction per unit time.
If the reaction proceeds between substances in a heterogeneous system, then the reacting substances do not come into contact with each other throughout the volume, but only on the surface. So, for example, when burning coal, oxygen molecules react only with those carbon atoms that are on the surface. When coal is crushed, its surface area increases and the burning rate increases. In this regard, the definition of the rate of a heterogeneous reaction is as follows:
B) The rate of a chemical reaction for a heterogeneous reaction.
For a heterogeneous reaction: The rate of a heterogeneous reaction is determined by the number of moles of substances that have entered into the reaction or formed as a result of the reaction per unit time per unit surface.
In mathematical form, this definition can be expressed as follows:
Question: How can the reaction rate be increased if the reactants are solid?
It is necessary to increase the contact surface of substances, i.e. crush the solid.
Therefore, for heterogeneous reactions, one of the factors that determine the rate of a chemical reaction is the size of the contact area of the reactants. Therefore, in production, chemical reactions in a "fluidized bed" are so often carried out. A solid substance for this purpose is finely crushed, crushed almost to the state of dust, and then a second substance, usually a gas, is passed through it from below. Its passage through the finely divided first substance - the reagent - is accompanied by the illusion of boiling. For example, in the "fluidized bed" the roasting of finely crushed sulfur pyrite is carried out in the production of sulfuric acid.
Knowledge of the rates of chemical reactions is of great practical and scientific importance.
In the lesson, we came to the conclusion that a chemical reaction must be considered not only from a qualitative and quantitative point of view, but also its speed should be taken into account.
This is necessary, first of all, in order to control the chemical reaction.
Don't forget that you are a cluster.
Factors affecting the rate of a chemical reaction.
We have considered what the rate of a chemical reaction is, we have determined that mathematically the rates of a homogeneous and heterogeneous reaction are determined differently.
Question: What determines the rate of a reaction?
We have listed the factors that affect the rate of a chemical reaction. You will have to investigate the reliability of these statements on your own, working in groups.
Task for groups:
Explain how the nature of the reactants, the area of contact of the reactants, concentration and temperature affect the rate of a chemical reaction.
Explanations can be scientific and figurative, related to everyday examples, artistic, you can sketch a situation that explains these phenomena.
Those. you need to create a model that should explain why and how the reaction rate changes. Your model can be: an explanation, a picture, a plot. To develop a figurative explanation, you can apply ANALOGY, i.e. what is this situation like? Time is given for group discussion, (10 min.)
Task number 1
Influence of the nature of reacting substances on the rate of a heterogeneous chemical reaction.
Exercise: explain why the nature of the reactants affects the rate of a chemical reaction.
Experience progress: Add pieces of zinc and magnesium to equal volumes of hydrochloric acid.
! Compare the rates of these two reactions.
! Explain the reason for the speed difference.
!
Task number 2
Influence of the concentration of substances on the rate of a chemical reaction.
Exercise: explain why the concentration of reactants affects the rate of a chemical reaction.
Experience progress: Pour equal volumes of sulfuric acid solution into 2 test tubes, simultaneously add sodium thiosulfate solutions of different concentrations (25 g/l and 200 g/l).
The reaction proceeds according to the equation: Na 2 S 2 O 3 + H 2 SO 4 = Na 2 SO 4 + H 2 S 2 O 3
H 2 S 2 O 3 \u003d H 2 O + S + SO 2
! Note the time after which the sulfur precipitate appears in the test tubes.
! Explain the reason for the uneven appearance of sediment.
Task number 3
Influence of the contact surface area of reactants on the rate of a heterogeneous chemical reaction.
Exercise: explain why the rate of a chemical reaction is affected by the surface area of the reactants.
Experience progress: Place a piece of chalk in one test tube, and crushed chalk in another, and add equal volumes of hydrochloric acid.
! Compare the reaction rates and explain the reason for their difference.
! Write an equation for chemical reactions.
Task number 4
Effect of temperature on the rate of a chemical reaction.
Exercise: explain why the temperature of the reactants affects the rate of a chemical reaction.
Experience progress: Prepare copper hydroxide: mix copper sulfate solution and sodium hydroxide. Pour the resulting copper hydroxide into two test tubes. Heat up one of them.
! Note the time it takes for black copper oxide to appear with and without heating.
! Draw a conclusion about the dependence of the reaction rate on temperature.
Task number 5
The effect of a catalyst on the rate of a chemical reaction.
Exercise: explain why a catalyst affects the rate of a chemical reaction
Experience progress: Pour the hydrogen peroxide solution into 2 test tubes. Heat one of them, add a little powder of manganese oxide (IV) to the other.
! What are you watching? Explain the result.
Analysis of the received data.
Listen to the performance of each group. We listen carefully and make a cluster.
For example:
1. Analogy to the influence of the nature of the reactants:
People come in different characters, different temperaments, and the speed of their work, the speed of rapprochement with other people depends on this. So substances have their own "characters" and this affects the rate of chemical reactions.
2. Analogy to the influence of the surface area of the reactants:
From an old sea song: “We are back to back at the mast, against a thousand, together!”. The heroes of this song reduced the area of contact with the enemies and reduced the "speed of reaction" with them, i.e., reduced the possibility of defeat.
3. Analogy to the effect of concentration:
The more substance per unit volume, the more collisions between molecules and the higher the reaction rate. It's like a big supermarket with a lot of goods and a lot of customers. A supermarket sells more product than a small specialty shop because the customer is "experienced" with a large number of different products.
Traffic jams. The concentration of cars is greater, and the speed of movement is less. Teacher's comment: yes, this also happens in chemistry: if the concentration of substances is too high, the reaction does not proceed, you have to dilute it with water so that the molecules "have somewhere to scatter."
4. Analogy to the influence of temperature:
When the temperature rises, the speed of the molecules increases, so they collide and react more often. It's like a disco where everyone is moving, dancing and therefore easier to get to know than, for example, at a meeting where everyone is sitting in their seats.
5. Analogy to the effect of a catalyst:
Two people are not friends, maybe even at enmity. The third decided to make them friends for the good of the cause. He goes to one of them, negotiates, unites with him, then they go together to another, agree again (with a mediator it is sometimes easier to negotiate), the mediator leaves, and the first two become friends!
Q: What are substances that speed up a chemical reaction called?
Teacher - So, we listened to each group, you reflected in your speech one of the factors that affect the rate of a chemical reaction.
QUESTION: Tell me, why do we need such figurative representations?
Answer: - For a better memorization and understanding of ongoing chemical processes.
Teacher - So, we looked at the performances of each group, each group reflected in their speech one of the factors that affect the rate of a chemical reaction. Let's see what cluster you have made.
Consolidation and generalization of the studied.
Task: And now for you a practical task:
In some laboratory, they tried for a long time to start a chemical reaction, but nothing worked, but then one of the laboratory assistants, when he was left alone in the laboratory, the reaction started! Everyone ran to see what he was doing to start the reaction, but to everyone's disappointment, nothing happened again .... Left alone, he again tried to carry out the reaction and ... she went again! It was worth calling everyone to show that there was no reaction ...
What's the matter here? If the laboratory assistant used only the usual means to start the reaction (heating, stirring, changing the concentration), then this would work in the presence of employees. And then he himself did not understand why he succeeds alone, but not with his colleagues.
To solve it, I offer you a TRIZ hint. There is in TRIZ (the theory of inventive problem solving) such a magic word MATHEM, which means a list of different influences
Hint for solving the problem:
M - mechanical (any mixing, pressure)
A- acoustic (sound)
T- thermal
X- chemical
E- electric
M - magnetic
Listen to the answers of the students, if the students did not come to the correct answer, then
the correct answer is given (the laboratory assistant sang when he conducted the experiment alone, but, of course, he was silent in front of everyone ...).
It turns out that sound can also affect the rate of a chemical reaction. Sound is vibrations, What factor does the effect of sound refer to? Why fluctuations can affect the start of a chemical reaction?
Vibrations help to mix the liquid, which means they increase the surface area of the reactants.
Using knowledge about the reaction rate in everyday life
Why is food stored in the refrigerator?
Inhibitors are used to preserve food.
What other name can be given to these substances? Name the preservatives that we use at home.
Homework. &15 used; & 14 p.o.
Summarizing.
Reflection. And now I will ask you to write me a telegram. It should not be more than 3 - 4 sentences of the telegraphic type, in which you will reflect your impression of our work today.
Thank you all for your cooperation.
RATE OF CHEMICAL REACTIONS 6.4.2 No. 86
Explanatory note.
This development of the lesson refers to the section "Chemical transformations" studied in the 11th grade. During the preparation of the lesson on the topic, the general requirements for the formation of classes were observed, such as the ratio of the principles of visibility, accessibility and scientific content of the proposed material, adherence to a culture of safe handling of substances and inculcation of a holistic worldview of chemical phenomena and processes, forecasting and planning the results of the lesson.
Clearly formulated goals and objectives of the lesson are implemented using various methods, forms and teaching methods. A lesson on the discovery of new knowledge with elements of research is proposed, since at this stage students will receive a sufficient number of theoretical concepts that are fixed during the implementation of the practical part of the lesson. The following forms of organization of educational activities were used: frontal, group, individual. The teacher has a role in regulating the learning process, directing students, monitoring their observations, correcting and supplementing their results and analyzing the latter.
Planned results: to form the basic concepts on the topic, to understand the significance of the influence of various factors on the rate of a chemical reaction. Understand the possibility of controlling a chemical reaction by changing the conditions for its occurrence. To develop the ability to plan and carry out a chemical experiment, skillfully recording the results, and analyze them. To realize the integrity of the ongoing chemical processes and phenomena, to carry out the variation of concepts as applied to the phenomena of the ecological and interdisciplinary spheres.
Lesson topic : the rate of chemical reactions.
Lesson Objectives : to study the essence of the concept: the rate of chemical reactions, to identify the dependence of this value on various external factors.
Lesson objectives:
educational What is the rate of chemical reactions and what factors does it depend on.
developing Students learn to process and analyze experimental data, reveal the essence of a chemical reaction, find out the relationship between the rate of a chemical reaction and external factors
educational Students develop communication skills in the course of paired, collective work. Attract the means of chemistry to understand the processes occurring in the world. In the course of practical work, they realize the obligation to strictly follow the instructions to obtain the result.
Lesson type : a lesson in the discovery of new knowledge with elements of research.
Teaching method : partially searchable, form of organization: individual, group, frontal, collective
Literature for teacher and student:
2. G.E. Rudzitis, F.G. Feldman Chemistry. Grade 11. Basic level / Textbook for educational institutions.
3. Gara N.N. Chemistry lessons 11 cells.
4. Gara N.N., Gabruseva N.I. Chemistry. Task book with "assistant" 11 cells.
Means of education:chemicals and equipment for experiments, multimedia console, computer.
Lesson stages | Justification of the teacher's activity | Predicted activities of students | Formed UUD |
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Mutual greeting of students and teacher; fixing absent; checking the readiness of students for the lesson. | Prepare students for work | Class readiness for work | Willingness to cooperate and co-create with the teacher |
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Let's remember:
| Lead students to consider the purpose and objectives of the lesson. Ensure students are motivated and accept the task of the lesson When discussing question (2), it must be emphasized that a chemical reaction is possible only when molecules collide | The active work of students shows their readiness to perceive the topic of the lesson. From personal life experience, students assume that the duration of various reactions is different. | To be able to participate in a collective discussion, to argue their position. Be able to use knowledge and everyday observations |
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We write down the topic of the lesson "The rate of chemical reactions." We formulate the task of the lesson: to find out what the rate of a chemical reaction is and on what factors it depends. In the course of the lesson, we will get acquainted with the theory of the question "the rate of a chemical reaction." Thenin practice, we will confirm some of our theoretical assumptions. | State the purpose of the lesson and a rough plan for its implementation. | |||||||||||||||||||||||||
Let's consider two examples. There are two test tubes on the table, in one - a solution of alkali (NaOH), in the other - a nail; Add CuSO solution to both test tubes 4 . What do we see? In the first test tube, the reaction occurred instantly, in the second - there are no visible changes yet. Let's compose the reaction equations (two students write the equations on the board):
Cu 2+ + 2OH - \u003d Cu (OH) 2
Fe 0 + Cu 2+ = Fe 2+ + Cu 0 Note that reaction 1) is homogeneous, and reaction 2) is heterogeneous. This is important for us. How long does the reaction last and what does it depend on? We will try to answer these questions during our lesson. The study of the rates and mechanisms of chemical reactions is calledchemical kinetics. | It is necessary to confirm the students' assumptions with a chemical experiment. | Based on the results of the demonstration experiment, students are convinced of the validity of their assumptions. | Be able to independently or with the help of a teacher record the results of a demonstration, draw a conclusion, plan a possible stage of study. Be able to write the equations of chemical reactions. |
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Let's turn to the concept of "speed". You know such combinations as the speed of movement, the speed of reading, the speed of filling the pool, etc. In general, what is speed? Change of any factor per unit of time. And what factor changes when it comes to the reaction rate? We have already said that a chemical reaction occurs when particles collide. Then, it is obvious that the rate of reaction is the greater, the more often the particles collide. When the particles of the initial substances collide, new particles are formed - the products of the reaction. What changes over time in a chemical reaction? The amount of starting substances changes and the amount of reaction products changes. If we relate the amount of a substance to a unit volume, we get the molar concentration of the substance. The molar concentration of a substance is measured in mol/l. to determine the reaction rate, it is necessary to have data on the change in the concentration of any component of the reaction at certain intervals. The reaction equation is written on the blackboard I 2 (gas) + H 2 (gas) + 2HI (gas) and a table of changes in the concentration of iodine over time is given (the right column - the change in the concentration of HI is not filled yet) | Ensure meaningful perception of knowledge Establish a factor by which one can judge the speed of a reaction Introduction of the concept of molar concentration and units of its measurement | Active actions of students with the object of study During the conversation, students come to the conclusion that the reaction rate is related to the concentration of substances involved in the reaction. | To be able to build causal relationships, to carry out the required comparison, generalization and dependence. |
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We build a graph of changes in the concentration of iodine over time С HI, mol/l 3 1,2 1,0 2 1,0 0,8 0,8 0,6 0,6 0,4 3 0,4 0,2 0,2 0 5 10 15 20 Time, s | A graph of changes in the concentration of a reactant over time gives students the opportunity to independently determine the reaction rate and track how it changes during the reaction. | Formation of research skills - build a graph according to the experiment | Be able to fix the dependence of the reaction rate on various factors. Formulate appropriate conclusions |
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The curve of change in the concentration of a reactant or reaction product over time is calledkinetic curve. The rate of a chemical reactionis the change in the concentration of one of the reactants per unit of time. C 2 - c 1 ∆c 0.3 - 1 v = = = = - 0.03 (mol/l s) T 2 – t 1 ∆t 20 – 0 It is customary to consider the reaction rate as a positive value, the minus sign indicates that the concentration dependence function I 2 diminishing from time to time. From the graph it follows that over time, not only the concentration decreases, but also the reaction rate. Let's confirm this with calculations. Let's determine the speed for different parts of the kinetic curve: in section 1: v = 0.08 mol / (l s), in section 2: v = 0.035 mol/(l s), in section 3: v = 0.01 mol/(l s) What conclusions follow from the analysis of the kinetic curve? – The concentration of the reactant decreases as the reaction proceeds. The reaction rate decreases over time. Obviously, the "rate of reaction" is the average rate of the process in a certain period of time, that the smaller the period of time, the more accurate the value of the rate. Fill in the right column of the table with the values of the concentration of the reaction product HI. When determining the values, we are guided by the reaction equation. We build a kinetic curve relative to the reaction product, determine the reaction rates for curve sections 1, 2 and 3. We conclude that the velocity in the HI component is twice as high as in the I component. 2 . This can be predicted from the reaction equation. additional analysis of the kinetic curve showed us that
| A step-by-step analysis of the kinetic curve leads to a meaningful understanding of the material being studied, eliminates the formalism of knowledge The construction of a kinetic curve for the reaction product shows that the accumulation of the reaction product occurs gradually, as the initial substances are consumed It is necessary to pay attention to the physical nature of the stoichiometric coefficients in the chemical reaction equation | Independently formulate the concept of "reaction rate" Independently calculate the speed for the entire kinetic curve and its individual sections. Students themselves derive units of the reaction rate Analyze the results of the obtained calculations. formulate conclusions | ||||||||||||||||||||||||
Poster on the board: The chemical reaction goes according to the scheme A + B = 2C 2A + B = 2C | Assess the correctness and awareness of the assimilation of new educational material, identify and eliminate gaps and misconceptions | Fill in the table | Be able to apply the acquired knowledge to solve simple problems. Analyze the correctness of the sequence of actions. Be able to participate in the discussion of the problem, express their own opinion about the result. |
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Task: in which of the vessels of the same capacity the reaction proceeds at a high rate, if at the same time 10 g of hydrogen fluoride is formed in the first vessel, and 53 g of hydrogen iodide in the second? | Consolidate the acquired knowledge | Independent performance of tasks with mutual verification of the result of execution. | Be able to independently solve tasks on the topic. Analyze the correctness of the task. |
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Let's sum up the main results. We formulate them and write them down in a notebook | To form the ability to summarize the information received and highlight the main thing | Independent formulation of conclusions. Identification of the general emotional and productive background of the lesson. | Be able to summarize and systematize the information received. Participate in discussions and be able to express your thoughts. |
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A multi-level task on cards is proposed: 1) mandatory: §.12, at 1-6 s. 62 2) in-depth: §. 12, z1-4 p.63 3) creative: Consider the reactions of obtaining sulfuric acid from pyrite in terms of the dependence of the chemical reaction rate on decomp. factors. | Accompanying the recorded task with comments for various levels. | Select one of the types of assignments for homework. Extracting the necessary information and fixing it in a diary. | Homework done correctly and with pleasure. |
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