Full transcript of “Chemical Reactions and Equations | Class 10 full chapter | Class 10 Science Chapter 1 in Animation”. Click a timestamp to open the video at that moment. Need another video? Use the YouTube transcript generator.
0:00 Hello everyone, from today we are going to start a new series in which we will cover each chapter in a very short time in the best possible animation so that you can understand everything well and you guys can prepare well for the board exams that too in a very short time. So let's start [Music] So in today's video we are going to study the first chapter of class 10th science which is chemical reactions and equations. So see, our chapter starts with changes. So we
0:45 get to see a lot of changes around us in daily life, out of which some changes are physical and some are chemical. The main difference in these changes is that the physical changes are reversible such as freezing of water and melting of water and the chemical changes are not reversible, meaning that once they happen, they do not reverse again. For example, rusting of iron. So when iron gets rusted and gets damaged, it cannot be repaired again because of chemical reactions. It is not reversible, so you people do not have to keep much confusion, you have to understand things simply that physical changes that happen cause physical reactions and chemical changes that happen cause
1:32 chemical reactions. So any chemical reaction has two main parts, reactants and products. Reactants are those substances that take part in the chemical reaction, while the product is the substance that is formed in the chemical reaction. By understanding chemical reactions, we will understand both these terms better. So chemical reaction is a process in which one or more substances called reactants are converted into one or more different substances called products. So it means that the reactants in a chemical reaction are converted into products. For example, hydrogen and oxygen
2:17 combine to form H2O i.e. water. So in this reaction, this hydrogen and oxygen are the reactants because hydrogen and oxygen are the only ones taking part in the reaction. And h2o is the product because h2o is being formed in the reaction, so after understanding about chemical reaction, now we have to see what changes we get to see during chemical reaction, so whenever a chemical reaction occurs, we can see a change in the state of reactants and products or we can see a change in their color, along with this we can also see a change in temperature and gas can also be seen coming out and within the chemical reaction itself we can also see the pristine state being formed, so in chemical reaction we can see some changes,
3:04 so next we have to understand chemical equations, so in this first we will see what are chemical equations, then we will see why we balance them, what is the need for us to balance them and in the last we will see how we balance chemical equations, so first we see what are chemical equations, so chemical equations are symbolic representations of chemical reactions and Writing chemical reactions with formulas, that is, in the form of their symbols and formulas is called a chemical equation. For example, carbon and oxygen combine to form carbon dioxide. So you see that this reaction is represented in the form of symbols in this way and this
3:50 representation is called a chemical equation. There is a way to write these chemical equations, in which the reactants are written on the left side and the products are written on the right side, as you can see in this reaction, next we have to see the balanced chemical equation, so a balanced chemical equation is an equation in which the number of atoms in both the left side and right side of the reactants and products is the same. Next we have to see why do we need to balance chemical equations, that is, why do we need to balance chemical equations, so we need to balance chemical equations. Because according to the law of
4:36 conservation of mass, the number of atoms in the reactants and products is not the same because if this is not the case then the law of conservation of mass will not apply. So we have seen that chemical equations should be balanced. Now let us see how these chemical equations are balanced. Chemical equations are not balanced by any specific method but by a simple hit and trial method. So
5:23 now if we try to balance a chemical equation, in this reaction iron is reacting with water to form iron oxide and hydrogen. So look at this reaction carefully. In this, the number of atoms in the reactants and products is not the same and this equation is unbalanced. So let us balance this reaction. So you have to remember one thing that for any change we make to balance any chemical equation, we have to make changes in each particular element or We enclose the compound in brackets. Then whatever we have to multiply or change, it is done on the entire element or compound which is in the brackets. So to make the balancing of chemical equation easy, we make a table in which we will write the names of the elements in one column, the number of atoms of the
6:10 reactants in the next column and the number of atoms of the products in the next column. So now we balance this reaction through the table. So the first element is iron. So there is one atom in the reactant of iron and you can see there are three atoms in the product. The second element is hydrogen. There are two atoms in the reactant of hydrogen and here in the product hydrogen also has only two atoms. And the third element is oxygen. So there is one atom in the reactant of oxygen and there are four atoms in the product. So in this table iron is first. So if we multiply the reactant side by three, then the number of atoms in both the sides reactant and product will be the same. Next is hydrogen. So you can see that hydrogen The number of atoms of oxygen is
6:55 same in both reactant and product which is two atoms and the last and third element is oxygen. So the number of atoms of oxygen in the reactant is one and there are four atoms in the product. So if we multiply the oxygen on the reactant side by four, then the atoms of oxygen on both sides will become equal. But we have just seen that if any two elements are given in compound form, then to balance it, the entire compound is multiplied. So we will multiply this h2o by four. So oxygen will be balanced by multiplying four in this h2o. But the hydrogen in the reactant will have eight atoms due to multiplying four. And it will become unbalanced because there are only two hydrogens in its product. So to
7:41 balance hydrogen, we will multiply the hydrogen of the product by four. So now you see in this reaction, all the three elements iron, hydrogen and oxygen have been balanced and the number of atoms in their reactants and products have become equal. As you can see in this You can see in the table that iron has three atoms each in the reactant and product, hydrogen has 88 atoms and oxygen has four atoms each in both the reactants and products. So the reaction that was written was unbalanced but we have now balanced all the elements in this table. So let us now write this reaction in a balanced way. So it will become 3fe + 4h 2o gives fe3 o4 + 4 h2. So now you must have understood
8:27 how we can balance chemical equations. You can also practice this by balancing some chemical equations yourself. The method of this is very simple, which I have told you. You have to form a table and in any way make the number of atoms in the reactants and products the same. Next we have to understand our next topic which is types of chemical reactions. So chemical reactions are basically of six types, which are combination reaction, decomposition reaction, displacement reaction, double displacement. Reaction Oxidation and Reduction Reaction and Azotic and Endorse Reaction So now we will understand all these reactions one by one with their examples so let's start with combination reaction so such reaction in which two or
9:13 more reactants combine to form a single product is called combination reaction its examples would be burning of coal so you see that when carbon burns in the presence of oxygen then CO2 gas is formed so what happened here is carbon and oxygen are combining to form CO2 gas i.e. two reactants which are carbon and oxygen are combining to form a product carbon dioxide gas another example of this would be formation of water so in this reaction you see hydrogen and oxygen are combining to form h2o i.e. water so you can see in both these reactions that the two reactants are combining to form a product these are called combination reaction after this the
9:59 second type of chemical reaction is decomposition reaction so decomposition means breaking so such chemical reaction in which a single When a reactant breaks down into two or more products, that is, it is called a decomposition reaction. So now you think why any reactant or substance breaks down. The answer is that any reactant or substance breaks down due to some energy. That means in the breakdown of a reactant or we can say in a decomposition reaction, some energy evolves and on the basis of this energy, the decomposition reactions that occur due to the breakdown of reactants are of three types, which are thermal decomposition, electrolyte decomposition and photoline
10:45 decomposition. So the first is thermal decomposition. Thermal means heat. So such a decomposition which is taking place by heat is called thermal decomposition. For example, when calcium carbonate ( C2) which is limestone is heated, then calcium oxide (C2) which is also called quick lime breaks down into CO2. The next decomposition is electrolyte decomposition. Such decomposition which happens through electricity is called electrolyte decomposition. For example, when electricity passes through H2 i.e. water, then the H2O present in it breaks down into hydrogen and oxygen. The third type of decomposition is photoline decomposition. The word
11:32 photo in science means sunlight. So such decomposition which happens through sunlight is called photoline decomposition. For example, when sunlight falls on silver chloride, it breaks down into silver and chlorine. So these were the three types of decomposition reactions which we had to understand. Next we have to understand the next type of chemical reaction which is displacement reaction. So this is such a reaction in which the more reactive element displaces the less reactive element from its compound or solution. For example, when zinc reacts with copper sulphate, then zinc is more reactive than copper. So, being more reactive, zinc displaces copper and forms zinc sulphate and copper gets separated as You
12:19 can see in this reaction that znso4 gives znso4 + s. So what happened here is that zinc, which was more reactive, displaced copper from its solution. Next and fourth type of chemical reaction is double displacement reaction. As its name suggests, two things are getting displaced in it. So a reaction in which two different ions or groups of atoms displace each other inside the reactant molecule is called double displacement reaction. You can understand it more simply like this: a reaction in which a part of one reactant gets displaced by a part of the other reactant is called double displacement reaction. To understand it more simply,
13:05 look at this equation: A P C D Gives A D P C B. So in this reaction, you can see that a part B of the first reactant went to the second reactant and a part D of the second reactant came to the first reactant and the product became A P C B. So, it means that a reaction in which two When there is displacement of two atoms or one ice, we call it double displacement reaction. So this was just an example to explain it to you. Its real example would be na2s o4 which is sodium sulphate plus bacl2 which is barium chloride. So when sodium sulphate and barium chloride react, sodium displaces barium from barium chloride and barium
13:50 displaces sodium from sodium sulphate, so baso4 barium sulphate. So such reactions in which there is exchange of ions between their reactants are called double displacement reactions. And in all these double displacement reactions, there are precipitators in most of them. Next, we have to understand the fifth chemical reaction which is oxidation and reduction reaction. So we will understand oxidation and reduction separately. So first is oxidation reaction. So oxidation is such a reaction in which oxide is being added or such a reaction in which hydrogen is being removed or such a reaction in which electrons are being lost. So in any reaction, oxidation is such a reaction in which oxide is being added or such a reaction in which hydrogen is being removed or such a reaction in which electrons are being lost.
14:38 Addition of oxygen or removal of hydrogen or loss of electrons in any reaction is called oxidation reaction. For example, carbon plus oxygen gives carbon dioxide. So, you see, this reaction is an oxidation reaction because oxygen is being added in it. After this, if you see this reaction, hydrogen sulphide is reacting with oxygen and water and sulphur are being formed. So, this reaction is also an oxidation reaction because hydrogen is being lost from hydrogen sulphide. And if you see this reaction also, in this, two electrons are being lost from zinc and two positive signs are appearing on zinc. This reaction is also an oxidation reaction because electrons are being lost in this reaction. After oxidation, now we have to understand the
15:25 reduction reaction. So, reduction reaction is the exact opposite of oxidation. So, reduction is such a reaction or a process in which oxygen is being removed or hydrogen is being added or such a process in which electrons are being gained. So, you can understand from these definitions that oxidation and reduction reactions are exactly opposite to each other. For example, When potassium chloride kclo3 breaks down, potassium chloride is a reaction that when sodium reacts with hydrogen, sodium hydride is formed. So you see, in this reaction hydrogen is being added to sodium, so this is also a reduction reaction. There is another
16:12 reaction in which two electrons are being added to zinc. So this reaction is also a reduction reaction because electrons are being added in it. So you should not have much confusion between reduction and oxidation reactions. You have to remember the simple definitions and examples that have just been explained. So the reactant or substance which is oxidized is called reduced. The oxidant or substance that is reduced is called reduced. And when oxidation and reduction reactions take place simultaneously in a reaction, that reaction is called a redox reaction. For example, zinc oxide zno2 + s. So you see, in this reaction, zinc oxide is being reduced to zinc and carbon is being oxidized to carbon monoxide.
16:58 Similarly, look at another example, cu2 gives cu2o. In this reaction, you can see that copper oxide is being reduced in copper and here reduction reaction is happening and hydrogen oxidation reaction is happening there. So, from the above two reactions, we can say that if a substance gains oxygen or loses hydrogen during the reaction, then it is called reduced. After this, we have to understand the last type of chemical reaction which happens
17:44 exhaustively, that is, heat is released. For example, burning of natural gas, when methane, that is, CH4, burns in oxygen, then CO2 and water are formed and along with it, a large amount of heat energy is released. Along with this, the reaction process that happens is an azoom reaction because in it, energy is released in the form of heat. After this, there is an endosylation reaction. So, this reaction is exactly opposite. When mercury oxide breaks down into mercury and oxygen, then a lot of heat energy is absorbed in that process. The most popular example is
18:29 photosynthesis. In the photosynthesis reaction, the heat energy of the sun is absorbed. Therefore, the reaction of photosynthesis is supported. After this, we have to understand the last topic of this chapter, which is the effect of oxidation in our daily life, that is, what effects of oxygen do we see in our daily life. So we mainly see two effects of oxygen, which are corrosion and rancidity. So first we look at corrosion. Corrosion is a phenomenon or a process in which the surface of the metal gradually starts deteriorating due to the reaction of air, water or any other chemical that is present in the atmosphere. Its examples will be, you all must have
19:14 seen that a black coating appears on silver, that is, a black layer is formed or a green layer appears on copper and if you have not noticed these two examples, then also there is no problem because you all must have definitely seen rust on iron. That also happens due to corrosion. In the case of iron, corrosion is called rust. So due to corrosion, a lot of car bodies, bridges, ships, iron railings and many other metals like silver and copper get damaged. So corrosion is a natural and slow process. It is not that any metal gets corroded in a day or two. And if we want, we can also prevent these metals from corrosion. For this, we just have to
20:00 take some simple steps like we can prevent corrosion by painting iron objects and we can prevent silver by not keeping it in external contact for long and cleaning it regularly. Along with this, we can prevent copper by making a paste of baking soda and salt and cleaning it regularly. So the corrosion that happens is very harmful for metals, but along with this, there is also a metal for which corrosion is very beneficial, that is, that metal benefits from corrosion which is In case of aluminium, corrosion is beneficial. After this, the second effect of oxygen is rancidity. This is the process of
20:46 slow oxidation of food materials in which oil and fat are present, which spoils the taste and smell of the food. So, you must have seen many food materials getting spoiled at some time or the other, like vegetables and many other food items get spoiled in our homes. The food materials get oxidized due to the presence of fat and oils, which spoils their smell and taste and it is also very harmful for our health. So, there are some methods to prevent food from rancidity, i.e. from getting spoiled. For example, we can keep food materials in airtight containers to prevent rancidity, so that they will not come in contact with air and will be prevented from rancidity. Along with this,
21:32 we can prevent the cooked food, which we cook ourselves, from direct sunlight. And we can prevent it by keeping it at low temperature in the refrigerator. Along with this, we can also prevent rancidity by adding antioxidants to the food material. So you must have eaten chips at some time or the other. When you must have eaten chips, you must have noticed one thing that the packet of chips is filled with more air than the chips themselves. So, have you ever wondered why chips are filled with gas or air and what is this gas that is filled inside the chips? The chips are mainly filled with nitrogen gas and it is filled because this gas prevents the chips from rancidity, that is, it protects them from oxidation. So, this was your
22:20 chapter. That's all for today's video. See you in the next video of this series. If you want, you can like this video and subscribe to this channel as well so that you don't miss any video of this series. I hope it has helped you. Till then, thanks for watching. Take care. Bye.
