Chemical Reactions- Definition, Equations, Types And Examples

Chemical Reactions: A chemical reaction is a process where the substances 8unbdergo a change in their chemical composition. The substances that enter the reaction are called reactants that are then transformed into new substances with different properties called products. 

Chemical reactions are all around us, from the burning of flames to the digestion of food in our bodies. 

Let us first know about physical and chemical changes. 

• Physical Change: In a physical change, the substance’s physical properties like shape, size and state transform, but the chemical composition remains the same. Take an example of treating a paper. The pieces are still paper but in different forms. 

• Chemical Change: In a chemical change, the arrangement of atoms within the substance is fundamentally altered, which leads the substance to change its shape. Bujrni9ng of wood can be a good example. 

Important Points To Remember

• Chemical reactions play an important role in different industries. They are also a part of our lives as well and continuously happen in our general surroundings like the rusting of iron or the fermentation of wine. 
• The rate of reactions depends upon and is affected by many factors like pressure, temperature and concentration of reactants. 
• A chemical reaction follows the law of conservation of mass, and the atom is destroyed or created but only a new product is formed from the reactants. 

Chemical Equations

A chemical equation is a mathematical statement that symbolises the product formation from reactants while stating certain conditions for how the reaction has been conducted. 

Well, the reactants are on the left side and the products formed are on the right side. 

Example: A+B= C+D

Here, A and B are reactants while C and D are the products formed. To ensure the law of conservation of mass, a chemical equation must be balanced. 

Types Of Chemical Reactions

1. Combination Reaction: In a combination reaction, two or more substances combine to form a more complex substance. 

Example: Hydrogen and oxygen gas combine to form water. 

2H₂ + O₂ → 2H₂O

2. Decomposition Reaction: In a decomposition reaction, a single compound breaks down into two or more simpler substances. 

Example: Calcium carbonate decomposes into calcium oxide and carbon dioxide when it is heated. 

CaCO₃ → CaO + CO₂

3. Neutralisation Reaction: In a neutralization reaction, an acid and a base react to produce salt and water. 

Example: The neutralisation reaction between hydrochloric acid and sodium hydroxide gives common salt as the main product. 

HCl + NaOH → NaCl + H₂O

4. Single Displacement Reaction: In a single displacement reaction, a more reactive element replaces a less reactive element in a compound. 

Example: When iron is placed in copper sulphate solution, then iron dispaces copper, leading to form iron sulphate. 

Fe + CuSO₄ → FeSO₄ + Cu

5. Double Displacement Reaction: In a double displacement reaction, two ionic compounds react and exchange ions to form two new ionic compounds. 

Example: Sodium sulphide when mixed with barium chloride, a precipitate of barium sulphide forms along with sodium chloride as a solution. 

Na₂S + BaCl₂ → BaSO₄↓ + 2NaCl

Video Lessons Links For Students

Jagran Josh has a special portal to provide video lessons for students that can help them understand the concepts easily. We are providing the links below: