[Music] chemical reactions and equations in our day-to-day life we see different changes around us like if milk is left at room temperature during summer it becomes sour and curdling takes place if an iron tawa is exposed to moisture it rusts if grapes are fermented they smell like alcohol if food is cooked its texture and taste changes when food is digested it is converted into useful nutrients when we respire food gets oxidized and releases heat and energy in all these cases the chemical nature of the initial substances is changed these kind of changes are called chemical changes a chemical change takes place due to a chemical reaction let let us see some examples of chemical reactions in lab setup when a magnesium ribbon is burnt in presence of oxygen it burns with a dazzling White Flame and white ash is obtained this ash is magnesium oxide when some potassium iodide solution is added to lead nitrate and lello precipitate is formed this L precipitate is nothing but lead iodite in the same way when a few Jin GR manuals are added to dilute HCL or h2so4 hydrogen gas is evolved heat is also released in this reaction in the above reactions we observed change in state change of color evolution of gas change in temperature along with change in chemical nature of the initial substance we also observe any of these changes in a chemical reaction so these observations help us to identify a chemical reaction chemical equation magnesium when burnt in presence of oxygen it produces magnesium oxide this is the verbal description of a chemical reaction this can be presented in the short form that is in the form of a word equation magnesium plus oxygen gives rise to magnesium oxide in this equation the starting materials magnesium and oxygen are called reactants and the final substance formed magnesium oxide is the product the reactants and products are separated by an arrow this Arrow Head points towards the products and shows the direction of the reaction reactants are always written on left hand side of the arrow and products are written on the right hand side there is a plus sign between the two reactants and between the products writing a chemical equation using chemical formulas magnesium plus oxygen gives rise to magnesium oxide let us write this equation using chemical formulas mg for magnesium and O2 for oxygen mg+ O2 gives rise to mzo here the number of atoms on the left hand side and right hand side are not equal that means this is an unbalanced equation such equations are called skeletal equations then how to balance a skeletal equation let's see balancing a chemical equation the law of conservation of mass states that in a closed system the mass of the reactants must equal with the mass of the products for any given chemical reaction it implies that atoms are neither created nor destroyed in a chemical reaction but they are rearrange it to form different substances that means the number of atoms of each element Remains the Same before and after a chemical reaction so we need to balance a skeletal equation to present it properly Fe + H2O gives rise to fe3o4 + H2 now let us balance this chemical equation step one when balancing a chemical equation begin with enclosing using each chemical formula within boxes do not change anything inside these boxes while working to balance the equation now tabulate the number of atoms of different elements present in this unbalanced equation ion number of atoms in the reactants is one and in the products it is three hydrogen number of atoms in the reactants two in the products two oxygen in the reactants one and in the products four step three sometimes it is easier to balance a chemical equation by focusing on the substance with maximum number of atoms this substance could be on either side of the equation for example if we have fe304 which has a lot of oxygen atoms if we look at the oxygen atoms on both sides there are four oxygen atoms on one side that is on right hand side and only one oxygen atom on the left hand side so we'll start by adjusting the number of oxygen atoms to make them equal on both these sides to balance the oxygen atoms the number of oxygen atoms initial in reactants it is one that is in H2O and in products four that is in fe304 so to balance it we'll multiply the one with four 1 into 4 in the reactants that means we are going to add four to the coefficient of H2O so to equalize the number of atoms we can put coefficient 4 as 4 h H2O now the number of oxygen atoms on both left hand side and right hand side are balanced step four now balance the hydrogen atoms to equalize the number of hydrogen atoms make the number of molecules of hydrogen as four on the right hand side so atoms of hydrogen in reactants it is8 in 4 H2O whereas in products it is only two so to balance it in the products we are multiplying two with four that means we are adding four as the coefficient for hydrogen atoms so now the equation becomes like this fe+ 4 H2O gives rise to fe304 + 4 H2 but still this is an unbalanced equation here ion is left unbalanced to equalize ion we take three atoms of Fe on the left hand side let's see atoms of ion initial in the reactants only one whereas in the products three F34 so now in the reactants we are multiplying one with 3 that means we are adding three as a coefficient for Fe now it becomes 3 Fe + 4 H2O gives rise to f304 + 4 H2 so now this is a balanced equation so step six now count the number of atoms on both sides to check whether the number is balanced on both sides or not this method of balancing is called Hit and Trail method step seven now writing the symbols of physical states to make a chemical equation more informative the physical states of the reactants and products are mentioned along with the chemical formula the gaseous liquid aquous and solid states of reactants and products are represented by the notations G for gases L for liquid AQ for aquous and S for solids respectively aquus is a solution in which water is the solvent sometimes the reaction conditions such as temperature pressure Catalyst Etc further reaction are indicated above and or below the arrow in the equation for example Co g means gas plus 2 H2 G that is gas gives rise to ch3 O L that means it's liquid and here on the Arrow we can see 3 40 ATM it indicates the atmospheric pressure in this reaction in the same way in the next reaction 6 C2 AQ that is aquous plus 12 H2 L that is liquid gives rise to C6 h126 Aquas that is glucose plus 6 O2 that is Aquas plus 6 H2O L liquid so this reaction takes place in presence of sunlight and chlorophyll these things are are mentioned on and below the arom mark it is to be noted that usually physical states are not included in a chemical equation unless it is necessary to specify them types of chemical reactions one combination reaction a combination reaction is a type of chemical reaction where two or more reactants combine to form a single product take some water in a beaker and add calcium oxide to it calcium oxide reacts with water vigorously and forms a precipitate that is calcium hydroxide large amount of heat is also released in this reaction in this reaction two reactants that is water and calcium oxide reacts and forms a single product that is calcium hydroxide such reactions are called as combination reactions the chemical reaction in which two reactants react to form single product is called a combination reaction some examples of combination reaction are one burning of coal carbon plus oxygen gives rise to carbon dioxide so here two reactants combining together and forming a product carbon dioxide and second one formation of water from H2 and O2 H2 + O2 gives rise to 2 H2O hydrogen plus oxygen gives rise to water here also two reactants hydrogen and oxygen are combining to form a product water so in this particular reaction heat is also released out the chemical reactions in which heat is released are called exothermic reactions some examples of exothermic reactions one burning of natural gas C4 + 22 gives rise to CO2 + 2 H2O in this reaction heat is released and one more example for exothermic reaction cellular respiration here the glucose reacts with oxygen and gives carbon dioxide plus water plus energy in this reaction also heat is released decomposition reaction a decomposition reaction is a type of chemical reaction in which a single compound breaks down into two or more simpler substances let us see some examples of it ferros sufate crystals are light green in color on heating the water in these crystals evaporates resulting in the formation of an an hydras feros sulfate the color of the crystals changes from light green to White now this compound decomposes to different substances the fic oxide sulfur dioxide and sulfur trioxide now let's see another example of decomposition reaction on heating calcium carbonate decomposes into calcium oxide and carbon dioxide it is an important decomposition reaction used in various Industries another example of decomposition on heating lead nitrate it decomposes to lead oxide nitrogen oxide and hydrogen we can observe the evolution of nitrogen oxide as brown fumes the decomposition reactions that takes place by heating are called thermal decomposition reactions all the above discuss the decomposition reactions or thermal decomposition reactions now let's see electrolytic decomposition if the decomposition reaction takes place by passing electricity such reaction is called electrolytic decomposition reaction example electrolysis of water the chemical equation for this reaction is 2 H2O in presence of electricity 2 H2 + O2 now let us see photolytic decomposition if the decomposition reaction takes place by the exposure to light is called photolytic decomposition when silver chloride is exposed to sunlight it decomposes into silver and chlorine gas the chemical equation for this reaction is 2 agcl gives rise to 2 AG + cl2 silver bromide also decomposes by sunlight 2 agbr gives rise to 2 AG Plus br2 in presence of sunlight the decomposition reactions require energy either in the form of heat light or electricity for breaking down the reactants the reactions in which energy is absorbed are known as as endothermic reactions now let us learn about displacement reaction gather three iron nails and clean them by rubbing with sandpaper obtain two test tubes labeled as a and b for approximately 10 mL of copper sulfate solution into each test tube securely tie two iron Nails together with a thread and carefully emiss them into the copper sulfate solution in test tube B for 20 minutes set aside One Nail for comparison later after 20 minutes remove the iron nails from the copper sulfate solution compare the intensity of the blue color of copper sulfate solution in test tubes A and B also compare the color of the iron Nails dipped in the copper sulfate solution with the one kept aside the following chemical reaction takes place in this activity ion plus copper sulfate gives rise to iron sulfate plus copper in this reaction has displaced Copper from the copper sulfate solution such a reaction is termed as a displacement reaction some other examples of displacement reactions jinc plus copper sulfate gives rise to Jin sulfate plus copper lead plus copper chloride gives rise to lead chloride plus copper since jinc and Lead are more reactive than copper they displace Copper from their compounds now let us see double displacement reaction a double displacement reaction reaction is a type of chemical reaction where two compounds react by exchanging ions to form two new compounds if we mix sodium sulfate and barium chloride solution we get a white precipitate in any chemical reaction if a precipitate is formed it's called a precipitation reaction in this reaction sodium chloride reacts with barium chloride and forms barium sulfate and sodium chloride here the barium sulfate forms the precipitate and the sodium chloride remains in the solution oxidation and reduction reactions if a substance gains oxygen during reaction then the substance is said to be oxidized and such reaction is called an oxidation reaction for example when copper powder is heat in presence of oxygen the brown colored surface of the copper powder turns black due to the formation of copper to oxide so when copper reacts with oxygen it forms copper oxide here can we get get back the Copper from copper oxide yes by a reduction reaction if a substance loses oxygen during a reaction it is set to be reduced and such reaction is called a reduction reaction when hydrogen gas is passed over heated copper oxide the black surface coating undergoes a transformation turning brown as the reverse reaction occurs and finally copper is obtained this reaction has both oxidation and reduction in it let's see copper oxide turning to Copper is a reduction reaction whereas hydrogen turns to water it is an oxidation reaction during this reaction copper oxide gets reduced by losing oxygen the hydrogen is gaining oxygen and is being oxidized so in other words one reactant gets oxidized while the other gets reduced during a reaction such reactions are called oxidation reduction reactions or simply redox reactions some other examples of redox reactions jinc oxide plus carbon gives rise to jinc plus carbon monoxide in the same way manganes oxide plus 4 HCL gives rise to manganes Chloride plus 2 H2O plus cl2 now let's see the effects of oxidation reactions in our day-to-day life corrosion when a metal is affected by substances around it such as moisture acids Etc it is said to be corroded and this process is called corrosion when iron is exposed to moisture it gets coated with a reddish brown powder this process is called as rusting of iron the black coating on the silver articles and the green coating on the brass items are the examples of corrosion rancidity when fats and oils are exposed to air they gets oxidized this leads to change in their smell and taste then those fats are said to be rancid fats and this process is called rancidity to prevent the oxidation of fatty foods the following preventive steps are followed adding antioxidant chemicals to the foods two keeping food in a tight container three filling the chips packets with nitrogen gas this is all about the chemical reactions and equations thanks for watching please like the video please share this video with your friends please subscribe to Great booster Channel press the Bell icon to get all the latest updates check the description to find Links of other useful videos