In the IIT JEE main syllabus, there are a total of 20 units given in the subject of Chemistry, unit number 8 is Thermodynamics, under which many important topics have been covered, and the Exothermic Reactions is one of such topics.
Also, in the IIT JEE Advanced, there is a chapter called Energetics, given in the syllabus of Physical Chemistry. In this chapter many important topics, such as Heat of reaction has been discussed, in which the Exothermic reaction again plays a role up to a certain extent.
Therefore, understanding the concept of Exothermic Reaction becomes important for the IIT JEE aspirants. But even more than understanding the concepts, knowing how it works in real life is even more important, and hence Vedantu provides the students of IIT JEE Chemistry the real-life examples of the Exothermic Reactions.
If you are looking for the study materials for the IIT JEE you can find them here: IIT JEE Study Materials - Free Online Study Material for JEE Main & Advanced - PDF Download (vedantu.com)
All About Exothermic Reaction
Exothermic reaction lets out heat when the temperature of the surrounding objects goes on increasing. But this process takes up the heat and makes the objects in the surroundings cool. On the other hand, the endothermic process takes up the heat and makes the surrounding atmosphere cool.
Exothermic is basically produced from a Greek word, ‘Exo’ meaning exterior, while ‘thermic’ means ‘heat’. In the chemical process, exothermic means heat moving outside. The exothermic reaction is a heat-generating chemical reaction.
Exothermic reactions generally take place in different day-to-day real-life activities. Here are some of the examples of exothermic reactions:
1. Making of an Ice Cube
Making an ice cube is a process of liquid changing its state to solid. Let's check this process, starting with water. A cup of water contains a large number of small particles of H2O molecules. Each small particle of the H2O molecule is moving and has some amount of energy. When an ice cube tray, filled with water, is placed in a freezer, it slowly loses heat and starts to cool down to become ice cubes. Changing water into an ice cube is an exothermic reaction.
2. Snow Formation in Clouds
Snow formation in clouds is also an exothermic reaction. Clouds come into existence from the condensation of water vapor. Some clouds have ice and there we get the heat from condensation as well as from crystallization. For exothermic reactions, it is the process that gives energy in the form of a heat body.
3. Burning of a Candle
In the case of burning a candle, the body of the candle carries paraffin, which is a hydrocarbon. When paraffin burns with the flame, it reacts with oxygen to create carbon dioxide and water. This reaction is certainly exothermic as it gives out heat to the atmosphere with the help of other products. The amount of heat released depends on the chemical reaction between the hydrocarbon and oxygen.
4. Rusting of Iron
The rusting of iron is a chemical reaction between iron & oxygen. When iron is in pure form or alloyed, rusting of iron takes place. In this process, heat gets released when iron comes in contact with oxygen. Basically, rusting is the formation of chemical substances that takes place due to the formation of moisture on the iron. For this reaction, the chemical formula goes as Fe2O3.xH2O.
5. Burning of Sugar
Inside the human body, sugar is a chemical reaction. It is formed by a combination of carbon, oxygen, and hydrogen. It releases heat once it goes inside the human body, resulting in the formation of energy. The heat goes out of the human body and gets added into the atmospheric heat. This process is called an exothermic reaction. But there are a few doubts which make it an endothermic reaction. For instance, when we put sugar in a bowl and burn it with a flame, it starts generating heat. It releases a huge amount of energy which makes it an endothermic reaction.
6. Formation of Ion Pairs
When ions are in gaseous form, it makes interacting with water, resulting in hydrated ions. This is an exothermic process. The smaller the ion radius, the bigger is the ion charge. Consequently, ion hydration enthalpy grows larger resulting in a concentrated exothermic reaction.
7. Reaction of Strong Acid and Water
As we know that heat is necessary to break a chemical bond. For example, Hydrogen chloride consists of a hydrogen atom H and a chlorine atom Cl connected by a covalent single bond which is a diatomic molecule.
HCl (Hydrogen chlorides) is in the form of a strong acid and when it gets mixed in water, the hydrogen ion reacts with water to make a more complex reaction. Since hydrogen ions are very tiny in size and a large amount of energy that is generated gets concentrated in a relatively smaller area. At this time, it draws the polar water molecules. The hydrogen ions result in the formation of a covalent bond with water and also attract a number of strong hydrogen bonds. So, this process is an exothermic process.
8. Water and Calcium Chloride
Calcium chloride, water, and baking soda mixed together (the experiment is done by the students in their school labs) produce a rise in the temperature by letting off heat into the atmosphere. This process is also known as an exothermic reaction.
9. Cold Packs to Heal an Injury
One other example of an exothermic reaction is a cold pack. If we apply a cold pack to the place of pain after an injury then it will be an exothermic reaction. The cold pack has two bags - an inner bag and an outer bag. The inner bag contains water in it while the outer bag has ionic salts. On pressing the cold pack, the water from the inner bag gets in touch with ionic salt and eliminates heat. Thus, the heat released to the atmosphere makes it an example of an exothermic reaction.
10. Laundry Detergent
Every time you don’t require a chemistry lab for experiments, sometimes things present around you are also useful for understanding the nature of reactions. The best example of this is the detergent powder. Simply dissolving laundry detergent in a bit of water generates heat. So, this is a process of an exothermic reaction.
11. Nuclear Fission
Nuclear fission is a unique exothermic reaction in which the nucleus of a heavy atom splits into pieces such as lighter elements and releases energy. In this process of Nuclear Fission, energy is released in the form of heat, kinetic energy, and gamma photons which is a form of high energy radiation.
Heavy atomic nuclei are bombarded with free neutrons which break the nucleus apart in nuclear reactors and bombs. As a result, the fission reaction releases more neutrons. So this is an example of an exothermic reaction.
12. Combustion Reaction
Combustion is an example of an exothermic reaction including materials like hydrocarbons reacting with oxygen to form combustion products such as water and carbon dioxide. Any combustion reaction is always involved with molecular oxygen O2.
For example, when wood burns, it must require the presence of O2 and a large amount of heat is produced. Wood is one of the common combustible items that is organic (a combination of carbon, hydrogen, and oxygen).
Respiration is the process of metabolism which is common in all living things. In this process, the living organism intakes oxygen and releases carbon dioxide. Food molecules get converted into simpler substances like glucose. Then the glucose is combined with oxygen and it provides energy to our body. This is called the respiration process and respiration is an exothermic reaction. The chemical equation is shown below.
C6H12O6 (aq) + 6O2 (g) 6CO2 (g) + 6H2O (l) +ENERGY
14. Thermite Reaction
Basically, a thermite reaction is an iron oxide (rust) reacting with aluminum to produce molten iron. The reaction is started by the formation of heat from the burning magnesium ribbon which is placed in the iron oxide/aluminum mixture. It is a mixture of iron oxide powder, aluminum powder and starts reacting when it is heated.
This reaction is an exothermic reaction and the equation is given below.
15. Neutralization Reaction
In the process of neutralization reaction, an acid and a base react to form salt and water. Also, in this reaction, the bonds are being made and energy is released to the surroundings.
For example The reaction between HCL (a strong acid) and NaOH (a strong base)
HCL (aq) + NaOH(aq) NaCL(aq) + H2O(l)
The complete ionic equation is –
H3O(aq) + CL-(aq) + Na(aq) + OH+(aq) Na+(aq) + Na+(aq) + Cl-(aq) + 2H2O(l)
The net ionic equation is regulated by removing the spectator ions (the ions present on both the reactants and the product side)
H2O+ (aq) + OH-(aq) 2H2O (l)
16. Barking Dog
It is an interesting exothermic reaction. In this reaction, you need a long glass tube, nitrous oxide and carbon disulfide. In case these chemicals are not available with you then there is an alternative solution – a bottle and rubbing alcohol. It is not as loud as the above reaction but it does produce a nice flame and an audible ‘woofing’ sound.
17. Decomposition of Vegetable
Decomposition of vegetables is also an exothermic reaction because microbes need the energy to break the bond of vegetables that’s why it produces heat energy. This process is largely carried out by soil invertebrate fauna and this decomposition is known as an exothermic reaction.
18. Solution of Sulfuric Acid in water
The processes of adding water into acid or acid into water are both exothermic reactions. The reason behind this is a number of possible factors, including increased entropy, as you are breaking a bond of hydrogen and chlorine atoms in hydrochloric acid, making new ions namely free chloride and hydronium.
The dissolution takes place in the two steps mentioned below:
H2SO4 + H2O H3O + HSO4-
HSO4-+ H2O H3O+ + SO42
Advantages of Studying the Real-life Examples of the Exothermic Reactions
Science is a practical subject, especially Chemistry, that is to say, the knowledge of practical concepts of chemistry is just as important as that of its theory.
A real-life example of Exothermic Reactions becomes rather easy to understand the theory by the real-life practical demonstration. Furthermore, it helps the students not only in understanding the concepts of Exothermic Reactions but also in remembering the same as well.
The real-life example also makes the students understand how the everyday things that happen around are the reason for Exothermic Reactions.
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