CHEMISTRY CHAPTER - 01

 CHEMICAL REACTIONS AND EQUATIONS

Course Content

I) Introduction

II) Types of changes

III) Chemical Reactions

IV) Chemical Equations

V) Different types of chemical reactions

VI) Oxidation and reduction reaction

VII) Oxidising and reducing agents

VIII) Balancing of chemical equations

IX) Corrosion and Rusting (prevention of rusting )

X) Rancidity

>Write the difference between physical and chemical change.

1)Physical change :-

➡️It is a temporary change. 

➡️It affects only physical properties i. e shape, size etc. 

➡️It involves very little to absorption* of energy. 

➡️For example - freezing of water, melting of wax, boiling of water etc. 

➡️It do not involve the production of energy. 

➡️No, new substance is formed. 

➡️It is easily reversible i. e original substance can be reformed. 

Chemical changes :-

➡️It is a permanent change. 

➡️It has both physical as well as chemical properties of the substance including its composition. 

➡️In this change, absorption and evolution of take place 

➡️Ex- digestion of food, burning of coal etc. 

➡️It involves the production of energy. 

Which is in the form of heat, light, sound etc.. 

➡️It is always accompanied(के सहित/साथ में ) by one or more substance.

➡️It is irreversible i.e original substance can not be recovered. 

Note point :-

➡️*Absorption - A process in which gas is taken up by a liquid or solid, or a liquid is taken up by a solid. 

➡️It is a bulk(विस्तार/ढेर ) phenomenon i. e the absorbed material is uniformly distributed throughout the body. 

>>Types of changes

➡️Physical change

➡️Chemical change

➡️Radioactive change(nuclear fusion) 

Due to chemical changes - 

➡️Change of state 

➡️Colour change 

➡️Gas evaluation 

➡️Temperature change 

Q) what is chemical reactions? 

Ans- 

It is a process in which one or more substances formed one or more substances. And it can't reversed by physical change. 

➡️Chemical reaction happens in our daily life-

📝Digestion of food

📝Respiration 

📝Rusting of iron 

📝Formation of curd

Q) Define :- 

1. Reactants 

2. Products 

Ans- 

1.) Reactants :- Who take part in chemical reaction. 

2) product :- The substance which are formed in a chemical reaction. 

Example-   A + B -> C + D

Here A and B are reactants and C and D are products.

Hydrogen + Oxygen  -> Water 

Q. What is chemical equation? 

Ans- 

The symbolic representation of a chemical equation in the form of symbols and formulae. 

Where reactants are written on the left hand side and products are on the right hand side. 

Q. What is chemical formula? 

➡️A symbolic representation of a molecule /compound is called chemical formula. 

Q. What is chemical symbol? 

➡️An abbreviation or shorthand sign for the full name of an element is called chemical formula. 

➡️Some important symbols are - 

* solid - s

* liquid - l

* gas - g

* aqueous - aq ( it is a solution in which solvent is water) 

*

Q. Why do we need to balance a chemical equation? 

Ans-

➡️Law of conservation of mass - matter can neither be created nor destroyed. 

➡️So number of elements involved in a chemical reaction should ramain same at reactant and product side. 

Types of chemical reactions click below 👇

Type of chemical reactions