Chemistry is a difficult school subject. It requires systems thinking, good knowledge and application of mathematics, knowledge of physics, the environment, etc. They begin to study chemistry in the 8th grade. You can interest and captivate children in a new subject, and facilitate the assimilation of new concepts, terms, and knowledge by involving various techniques of interesting techniques, demonstrations of reactions, etc. in the explanation of new material. The most striking are the lessons using information and communication technologies. This section to help the school chemistry teacher was created with the goal of sharing available materials: lesson plans, chemistry presentations, work programs, etc.
Various materials to help a school chemistry teacher
- Fun challenges for chemistry lessons
- Lesson. Essential chemical concepts
- Innovative model of work of the Republican Educational Institution of Chemistry and Biology “Increasing the professional competence of a chemistry and biology teacher in the context of updating the content of education”
- Certification: Chemistry Teacher Portfolio
- Brochure. Russian vocabulary in chemical terminology
- Specifics of a monologue-speech at a scientific-practical conference
- Report on the work done in chemistry, biology and ecology
- Educational program of the chemical-ecological circle
- Master class: “Organization of student research activities”
- The use of active forms of learning for the development of student cognitive competencies in the context of the implementation of the Federal State Educational Standard for basic general education
Educational quest in chemistry and biology
In the process of working on such a quest project, students comprehend real processes and experience specific situations. From the point of view of information activities, when working on a quest project, its participant requires the skills of searching, analyzing information, the ability to store, transmit, compare and synthesize new information based on comparison.
Compliance with the characteristics of the target group (age, psychological, social, etc.)
The questions are compiled approximately for the age of students in grades 7-9, since at this age students become familiar with such a subject as chemistry, and study biology from the 5th grade. However, if desired, teams from grades 5-6 can take part.
The socio-psychological characteristics of the participants are taken into account, because Modern teenagers 13-16 years old are characterized by low concentration, attention deficit disorder and hyperreactivity, a desire to learn as much information as possible in a short time, are spreading among them. It is for this reason that they prefer to watch rather than read. The Internet also taught them to “cross” perceive information - they are accustomed to working with materials filled with hyperlinks. Therefore, the quest moves into a virtual environment, which also allows you to reach a wide range of participants, removing restrictions on time and distance of participants. The use of Web 2.0 services also makes them interesting and relevant for teenagers.
Structure and content of the quest
The quest consists of several stages:
Registration of teams “Let's get to know each other” (https://sites.google.com/view/rmo-cim-bio-votruo/ecobiochemist-2020/let's-get to know each other) Students create a playcast with information about the participating team. Data is also entered into a promotion table made in Google Sheets. Teams post a link to the promotion table, where other students can become familiar with the team and its presentation. The page contains a training video explaining how to use the Web service.
Stage “Science forged victory”
dedicated to chemists and biologists (https://sites.google.com/view/rmo-cim-bio-votruo/ecobiochemist-2020/science-forged-victory). Participants put together a puzzle in the service https://www.jigsawplanet.com/identify the scientist depicted on the puzzle, enter his name on the form, and note his achievements during the Second World War. Answers are entered using a form created by Google.
Stage “What? Where? When? How?"
(https://sites.google.com/view/rmo-cim-bio-votruo/ecobiochemist-2020/what-where-when-how) Team participants answer questions in a quiz created using the Google Forms service. The questions focus on advances in chemistry and the role of animals in the fight against invaders. The questions are composed with one answer option or with several; the quiz contains questions where you need to briefly write down your answer.
Research papers in chemistry
- Research work “The influence of energy drinks on the human body”
- Research work “Study of iodine content in the body of students and the food they consume”
- Study “Determination of lycopene in tomato products”
- Research work “Table salt and its properties”
- Research work “pH of cosmetics”
- Research paper "The Great and Terrible Bisphenol-A"
- Research work “Study of the physical and chemical composition of water at the site of the Sterlitamak meteorite fall”
Entertaining chemistry, Chemistry for children, Entertaining chemistry for children
Entertaining chemistry for preschoolers: benefits and benefits
All preschool children are highly inquisitive. When a child sees something new, he immediately reacts accordingly. Thanks to the abundance of modern media, children have access to a large amount of information, and it is important for adults to help the child choose what he needs and direct this flow in the right direction. All children have a natural thirst for knowledge, and this curiosity needs to be satisfied, not suppressed. Children little by little put together the acquired skills into a holistic picture, learning the world in its entirety.
The main way to get to know the world around us is through trial and error, the experimental path. When a child not only receives theoretical knowledge, but also actively tests it in practice, the skills are reinforced and remain in memory for a long time. Entertaining chemistry classes are designed specifically for practical exercises and perform the following tasks:
- They create the necessary conditions for preschoolers to fully acquaint themselves with the world around them and its diversity.
- They create the necessary conditions for understanding how various materials, as well as natural phenomena, interact with each other.
- Allows you to gain first experience in the practical application of existing knowledge.
- They learn to systematize the information received.
- Create conditions for observing experiments conducted by adults.
A special feature of the “Entertaining Chemistry for Preschoolers” program, which teachers at Erudite children’s centers recommend for attendance, is designed to gradually complicate the material, as well as use the knowledge already acquired by the child by this period.
Materials used in classes
In entertaining chemistry classes, various books, encyclopedias, puzzles, other teaching materials and visual aids are often used. Each child has the opportunity to independently choose the type of task, according to the level of their knowledge and capabilities.
In addition, the classroom provides places where children can put their acquired knowledge into practice, conduct experiments under the guidance of adults, and experiment with the interaction of certain chemicals.
The advantages of “Entertaining Chemistry” are that the material is presented in a simple and accessible form, using vivid facts and demonstrating exciting experiments similar to magic tricks, so children are never bored in class.
Attendance at classes is entirely optional. If at some point a preschooler wants to change the environment and leave the room, no one forbids him to do this, since everyone’s level of perception of information is different, and some can listen to the teacher for a long time, while others get tired quickly.
Many adults are still not very interested in the subject of chemistry, for one simple reason: they do not understand the subject, and their children also need help in this area. It is important to have a good teacher who can correctly and clearly explain the action and influence of chemical reactions and demonstrate them through experiments and experiments. When presented correctly, classes turn into a fun and easy process.
You can learn quite a lot of interesting facts and get a lot of information from books and the Internet. However, a lot of amazing things can be learned just by observing the world around us.
For some, this will be an amazing discovery, but almost everything that surrounds us is somehow connected with chemistry. Even we ourselves are made up of numerous chemical reactions that occur within us. This process combines all the exchanges that occur in the body, and we are 70% water.
Chemistry is a very important science, and it largely explains the processes occurring in nature. We can not only observe the interesting world around us, but also understand why the leaves fall in the fall, why our house is built of such hard bricks, why we feel thirsty, hungry, and so on. All this knowledge will be needed in our lives to avoid mistakes. Also, using our knowledge, we can create something new and useful for society.
For the experiments, we will only need those things that we already have at home or can buy in the supermarket. The main condition is that we must know what chemicals need to be added to get the required reaction, and do it safely. This is why it is so important to know chemistry and chemical elements, their nature and structure.
Did you know you can turn on a light bulb with a match, use manganese crystals to polish a pan, and light a candle with a sugar cube? Simple objects can work wonders. But there is nothing incredible about this, chemical reactions just occur. Graphite and diamond are almost the same thing, carbon, but the differences in the crystal lattice make them what they are. Diamond is a very hard gemstone, while graphite is soft and is used in regular pencils.
People are naturally curious and always want to learn about new things to understand why and how things happen. Chemistry, along with biology, physics and mathematics, explains it all. Therefore, we need to study all sciences, and not just those subjects that we like. It's always interesting to learn something new and use it in everyday life. For example, make plasticine with your own hands, light a fire, conduct experiments and observe the reaction. You can start with the simplest experiments, such as water ones.
What can you experiment with in chemistry? Stereotypes portray us as a lot of bubbling beakers, and it is true that chemistry is associated with various reactions. However, this science also includes matter, change, and the list goes on and on.
Why do children need science?
Science encourages curiosity and asking questions. Science activities also encourage problem-solving and observation skills. Even a toddler can enjoy a simple science experiment. Take, for example, a basic science experiment involving baking soda.
Above all, encourage your children to never stop asking questions, and by all means try to answer them as thoroughly as possible, or better yet, show them how they can find the answers together. Parents don't have to know everything! But we help our children find the answers they are looking for.
Simple chemical reactions for preschoolers
These simple science experiments are safe and educational, and can be made from materials found in almost every home.
It's easy to find ways to teach biology and physics to young children because there are plenty of examples in everyday life. But teaching chemistry to toddlers and preschoolers can feel more challenging because we are limited in the chemicals that preschoolers can safely explore. The best way is to enroll your child in entertaining chemistry classes, where, under the guidance of experienced teachers, children can learn the basics of science.
However, simple chemical experiments can be done at home with your kids. The components used in these experiments are quite safe, as are the reactions that occur (although experiments must be carried out under adult supervision).
These chemical reactions are perfect for homeschooling and are a great way to introduce science to young children.
Baking Soda Experiment
This preschool science experiment is as simple as it gets, but quite fun. By exploring this chemical reaction, children will see what happens to vinegar when it reacts with baking soda.
If you add food coloring, the experiment will also be interesting from an artistic point of view.
Consumables:
- pot; - plastic mug; - a box of baking soda; - food coloring (optional); - pipettes; - white cardboard.
Pour baking soda into the pan and spread it into an even layer. Have children sprinkle various food colors into baking soda. Fill a plastic mug with vinegar. Have children use eye droppers to drop vinegar into the baking soda. As they watch the sizzling chemical reaction, they can place white cardstock on top to imprint and keep a colorful impression!
Cola+Mentos explosion
It is recommended to do this experiment outdoors, since the chemical reaction results in the formation of a rather tall geyser.
Consumables:
- a bottle of diet or regular cola; - original Mentos.
Using a large container or just an open space, open a bottle of Diet Coke and have kids drop Mentos into the bottle. Step back quickly and enjoy the results of the experiment!
Sand volcanoes
Consumables:
- sand; - water; - baking soda; - vinegar; - bottle for water; - food coloring.
For a more foamy volcano eruption, you can add a few drops of dishwashing detergent.
Fill the water bottle about a third full (mix water with food coloring). Add about 5 teaspoons of baking soda. Screw on the lid.
Build a sand mountain around the bottle. Open the cap of the bottle and pour 150-200 g of vinegar into it. Now run to the side and watch the powerful “volcanic eruption”!
Magic balls
Consumables:
- baking soda; - vinegar; - empty water bottles; - balloons; - measuring spoons; - funnel.
Inflate and deflate the balloon a little to stretch it. Use a funnel and a teaspoon to add baking soda to the inside of the balloon (2-3 teaspoons per balloon). Fill the bottles (partially) with vinegar. Gently but carefully attach the balloons to the necks of the bottles, and then lift the balloons slightly so that the baking soda from them falls into the container with the vinegar. Watch the balloon magically inflate! To achieve a better effect, you can shake the bottle a little.
By the way, before filling the balloons with soda, you can draw emoticons, shapes or funny pictures on them.
The science behind this baking soda experiment is a chemical reaction between an alkali (baking soda) and an acid (vinegar). When these two ingredients are mixed together, a reaction begins.
The gas produced from these two components is carbon dioxide or CO2. When the gas tries to leave the plastic bottle, it rises into the ball due to the seal you created. Since the gas has nowhere to go and is pressing on the balloon, it inflates it! In the same way, we exhale carbon dioxide when we inflate balloons.
Experiment "Ice Needle"
For the experiment from the “Entertaining Chemistry” series, we will need water, salt and ice cubes. Pour water into an ice cube tray and freeze it. Then take 18 cubes and place them in a triangle shape and then pour salt between the cubes. The cubes stick to each other, and we get a long and thick “needle”. By the way, the water can initially be painted a different color or ice cubes can be laid out in a different shape, for example, a pyramid. Children will definitely love this experiment.
How to grow a crystal
You can even grow a crystal at home. First, dissolve a large amount of salt in water. Then place the tree branch into the liquid. Over time, crystals will begin to grow on the branch. Then coat the crystals with varnish so that they can last long enough. You can also grow beautiful crystals from sugar.
Experiment "Tornado"
For this experiment, take a plastic bottle, water, dishwashing liquid, and glitter. Fill the bottle halfway with water, add two drops of dishwashing liquid and add glitter. Turn the bottle upside down and spin it. Then stop it with your hand and you will see a real “tornado” inside the bottle. It's amazing! In this way, schoolchildren can study centrifugal force. This is all clear and understandable even to a small child, and the students will also learn something. Fun chemistry allows you to learn everything without tedious studying.
You can learn a lot at home and get your kids interested in something as exciting as chemistry. When they become adults, they will be grateful to you, remembering the fun chemistry lessons all their lives as something very special.
Bring your children to fun chemistry classes at Erudite children's centers!
Chemistry Presentations
- Chemistry presentation: Experiment with flowers
- Presentation: White magic lesson
- Presentation: Combustion of magnesium in carbon dioxide
- Chemistry Presentation: Nomenclature of Alkanes
- Presentation: Theory of chemical structure by A.M. Butlerov
- Why is chemistry needed?
- Presentation: The effect of energy drinks on the human body
- Presentation on chemistry “Isomerism and its types”
- Presentation: “Technology of problem-based dialogue learning”
- The self-presentation “Let me introduce you” will be of interest to those chemistry teachers who will participate in the “Teacher of the Year” competition
- Presentation: “Requirements for a modern lesson in the context of the implementation of the Federal State Educational Standard”
- Presentation on chemistry “Fascinating experiments”
- Chemistry presentation “Tips for a research director”
Chemistry assignments. Grade 11
Problem 1
There was an acetylene leak at an industrial plant. To determine the explosiveness of the resulting acetylene-air mixture, 20 liters of it were passed through a solution of potassium permanganate acidified with sulfuric acid. As a result, 11.3 g of potassium permanganate was reduced. Is the concentration of acetylene in the air dangerous if such mixtures explode at an acetylene content in the range of 2.0-81% (in volume fractions)?
Solution:
The interaction of an acidic solution of potassium permanganate with acetylene proceeds according to the equation
2 KMnO4 + C2H2 + 3H2SO4 = 2MnSO4 + K2SO4 + 2CO2 + 4H2O
According to the reaction equation x
= (11.3·22.4)/316 = 0.8 l, thus, the volume fraction of acetylene is 0.8/20 = 0.04 or 4%. The mixture is explosive.
Problem 2
By fusing iron (III) oxide with an oxidative-alkaline mixture (based on KOH), a salt containing 28.3% (wt.) iron was obtained. After removing other reaction products, the said salt was transferred to an air-filled closed vessel with a volume of 1 liter (n.s.). Water was also added to the vessel in the amount necessary for its complete hydrolysis. As a result, the pressure in the vessel increased by 0.192 atm. Which salt was hydrolyzed and what quantity (g) of the original iron(III) oxide was consumed? (The volume occupied by the reagents and water in the vessel can be neglected).
Solution:
1. Let us define the iron salt obtained by fusing iron (III) oxide with an oxidative-alkaline mixture. As a result of this process, an alkali metal ferrate (in our case potassium) is obtained, in which iron is in its maximum oxidation state of +6. Let's write down the equation of a possible reaction:
Fe2O3 + 3KNO3 + 4KOH → 2K2FeO4 + 3KNO2 + 2H2O. (1)
The mass fraction of iron in potassium ferrate is 28.28% (mass) ((56·100)/198), which is in good agreement with the problem conditions. So, the salt containing iron is potassium ferrate
.
2. Let us write the equation for the hydrolysis of K2FeO4:
4K2FeO4 +10H2O → 4Fe(OH)3 + 3O2↑+ 8KOH. (2)
From equation (2) it is clear that as a result of the hydrolysis of K2FeO4, oxygen is released.
Let us calculate the molar composition of air with a volume of 1 liter under normal conditions ( T
=273 K,
p
=1 atm) assuming that the air composition (by volume percentage) is: N2 – 78%; O2 – 21% and CO2 – 1%. Assuming the state of these gases to be close to ideal, we can calculate:
n(N2) = 0.78 (l)/22.4 (l/mol) = 0.0348 mol; n(O2) = 0.21 (l)/22.4 (l/mol) = 0.0094 mol; n(CO2) = 0.01 (l)/22.4 (l/mol) = 0.00045 mol.
Since the air contains CO2, it will be absorbed by hydrolysis products (in particular, KOH) and therefore must be excluded when determining the composition of the final gas mixture.
Using the equation of state of an ideal gas, we determine the number of moles of the gas mixture after hydrolysis of K2FeO4:
n
(N2 + O2) =
pV
/
RT
= (101325·(1+0.192)·10-3)/8.314·273=0.0532 mol.
The amount of K2FeO4 released as a result of hydrolysis is equal to:
n
(O2)hydrolysis =
n
(N2 + O2) -
n
(N2)ref.
- n
(O2)ref. = 0.0532 - 0.0348 - 0.0094 = 0.0090 mol.
3. Using reaction equation (2), we find the amount of K2FeO4 subjected to hydrolysis:
from 4 moles of K2FeO4 3 moles of O2 are formed,
from x
1 mol K2FeO4 produces 0.009 mol O2,
hence x
1 = 0.012 mol.
4. Using reaction equation (1), we find the amount of Fe2O3 spent to produce 0.012 mol of K2FeO4:
from 1 mole of Fe2O3 2 moles of K2FeO4 are formed,
from x
2 mol Fe2O3 produces 0.012 mol K2FeO4,
hence x
2 = 0.006 mol, which is 0.96 g.
Answer:
K2FeO4;
m
(Fe2O3)=0.96 g.
Problem 3
Propose a reaction scheme for obtaining 2-chloro-4-nitrobenzoic acid from inorganic substances.
Solution:
Problem 4
Compound X
obtained from the reaction between cobalt (II) chloride, ammonia, ammonium chloride and an oxidizing agent.
Chemical analysis of substance X
gave the following results (wt.%): Co – 25.3;
N – 24.0; H – 5.14 and Cl – 45.6. Treatment with 1.00 g of X
silver nitrate solution gives 0.614 g of silver chloride.
Derive the formula for X
and name the compound.
Prove the structure and draw the structure (or structures)
of
X. Draw the structure of compound Y
, which will be obtained if H2NCH2CH2NH2 is used instead of ammonia.
Name the
connection
Y. What class do compounds X
and
Y
?
Solution:
- Let's determine the gross formula of the substance X
.
From the conditions of the problem it follows that 100 g of substance X
contains 25.3 g Co, 24.0 g N, 5.14 g H and 45.6 g Cl.
From here we can calculate the molar ratio of the components in substance X
:
n(Co)/n(N)/n(H)/n(Cl)=(25.3/59):(24.0/14):(5.14/1):(45.6/35.5)=0.43:1.71:5.14: 1.28
or
n(Co)/n(N)/n(H)/n(Cl)=1:4:12:3.
Thus, the simplest formula of substance X can be written as:
CoN4H12Cl3.
A substance of this composition is obtained by the interaction of CoCl2 with NH3(aq), NH4Cl and an oxidizing agent (the latter can be hydrogen peroxide or air oxygen). The chemistry of cobalt is characterized by the formation of complex compounds, among which the main group consists of compounds with a coordination number for cobalt equal to 6
.
Based on this, we can write down the reaction for obtaining compound X
, having the composition CoN4H12Cl3:
CoCl2 + NH4Cl + 3NH3 + (0.5H2O2) → [Co(NH3)4Cl2]Cl + H2O. (1)
The compound [Co(NH3)4Cl2]Cl is called: tetraamminedichlorocobalt (III) chloride.
2. Proof of the structure of substance X
is the reaction with AgNO3:
[Co(NH3)4Cl2]Cl + AgNO3 → [Co(NH3)4Cl2]NO3 + AgCl. (2)
From equation (2) it follows that 0.614 g of AgCl is indeed formed from 1 g of [Co(NH3)4Cl2]Cl: 1/233.5=0.614/143.5=0.0043. It follows that there is only one chlorine atom in the outer coordination sphere of the complex compound CoN4H12Cl3, which confirms our assumption that substance X is tetraammine dichlorocobalt (III) chloride.
The compound [Co(NH3)4Cl2]Cl has two possible isomers:
Chloride cis
-tetraammine dichlorocobalt (III) and
trans
-tetraammine dichlorocobalt (III) chloride.
3. If instead of NH3 we use H2NCH2CH2NH2 (1,2-diaminoethane, ethane-1,2-diamine), we obtain the compound di(ethane-1,2-diamine)dichlorocobalt (III) chloride ( Y
),
cis
- and
trans
-isomers of which are represented by two optical isomers (enantiomers):
4. The compounds considered belong to the class of complex compounds. Y connection
called a chelate.
The H2NCH2CH2NH2 ligand is called chelating
or
chelating
.
Problem 5
When treated with a nitrating mixture of aromatic substance A
, the molecular formula of which is C8H10, predominantly two substances are formed,
B
and
B'
, with the molecular formula C8H9O2N.
When substance A
with an acidified aqueous solution of KMnO4, substance
C
with the molecular formula C7H6O2.
B
and
B'
under the same conditions gives isomeric substances
D
and
D '
.
Establish the structure of substances A
,
B
,
B '
,
C
,
D
and
D '
. Give complete reaction equations.
Solution:
Substance A
may have the following structural formulas:
Since during the oxidation of A
a compound with a smaller number of carbon atoms is formed - C7H6O2, or C6H5COOH, substance
A
is ethylbenzene (formula I).
The transformations described in the condition of the problem can be expressed by the following schemes:
Problem 6
In a volume ratio of 3:3:4, 0.3 N, 0.1 M and 0.6 N were mixed. orthophosphoric acid solutions. Calculate the concentration of hydrogen ions in the resulting solution, taking into account that the degree of acid dissociation in the first step in it is 20%. What is the pH of the resulting solution? The dissociation of the acid through the remaining steps can be ignored.
Solution:
- Let's move from the normal concentration of the initial solutions to the molar one. Since the equivalence factor of H3PO4 is 1/3, we have
WITH
M =
C
H/3.
Thus, in a ratio of 3:3:4, 0.1 M, 0.1 M and 0.2 M solutions of orthophosphoric acid were mixed, respectively
- Let us assume that 3 liters of 0.1 M, 3 liters of 0.1 M and 4 liters of 0.2 M solutions of H3PO4 are taken. Then the final solution (10 L) will contain 1.4 mol H3PO4. The result is a solution of 0.14 M ( WITH
M=n(H3PO4)/
V
(solution)=1.4mol/10 l=1.4 mol/l (M)). - If we take into account the dissociation of H3PO4 only in the first stage:
H3PO4 ↔ H2PO4— + H+,
it follows that from each mole of H3PO4 that undergoes dissociation, 1 mole of hydrogen ions is formed. Since the degree of dissociation is 20%, 0.028 mol/L H3PO4 dissociates in the solution and therefore the concentration of hydrogen ions is 0.028 mol/L.
- By definition, pH=-log[H+]. Hence pH=-lg0.028=1.55
Answer:
SM(H+)=0.028 mol/l; pH=1.55.
Problem 7
From benzene and other necessary reagents, obtain 4-bromo-3-nitrobenzoic acid ( A
) and 4-bromo-2-nitrobenzoic acid (
B
).
Justify the choice of the sequence of transformations and name all intermediate products. Then obtain
esters A
and
B
Solution:
Obtaining product A
:
In the first stage, Friedel-Crafts alkylation occurs, followed by Friedel-Crafts bromination. Next is oxidation to benzoic acid and nitration. At the last stage, a coordinated orientation of the nitration reaction occurs ( A
). Esterification reaction:
Receiving Product B
:
In the first stage, Friedel-Crafts alkylation occurs, followed by Friedel-Crafts bromination. Next, nitration of 4-bromotoluene occurs (inconsistent orientation). The nitro product is oxidized to benzoic acid ( B
). Esterification reaction:
