CLASS 10th

NOTES CHAPTER 1 CLASS 10TH Chemical Reaction and Equations

                                           Chemical Reaction and Equations

Exothermic and Endothermic reactions

Exothermic Reaction

A chemical reaction which is accompanied by evolution of heat energy is known exothermic reaction.

 Endothermic Reaction

A chemical reaction which is accompanied by absorption of heat energy is known as endothermic reaction.

Skeletal equation

A skeletal equation equation  is an equation in which various reactants and products are represented by their respective formulae but no attempt is made to equation the number of atoms of various elements on both the sides of the equation.

Balanced chemical equation

An equation in which number of atoms of each elements is equal on both the sides of the equation is known as balanced chemical equation.

Types of chemical reactions

  1. Combination reaction.

  2. Decomposition reaction.

  3. Displacement reaction.

  4. Double displacement reaction.

  5. Oxidation and Reduction.

  6. Isomerization Reactions.

Combination reaction

The reactions in which two or more substances combine to form a single new substance are called combination or synthesis reactions.

Decomposition reaction

The decomposition reaction generally take place when energy in some form such as heat, electricity or light is supplied to the reaction.

Displacement reaction

The chemical reactions in which one element displaces another element from a compound and takes it’s place are known as displacement reactions.

Double displacement reaction

The reactions in which two compounds react to form different compounds by mutual exchange of ions called double displacement reactions.

Oxidation and Reduction ( redox reaction)

Oxidation Reaction

Oxidation is a process of addition of oxygen or removal of hydrogen to a substance.

Reduction Reaction

Reduction is a process of removal of oxygen or addition of hydrogen to a substance.

Oxidising and Reducing agents

Oxidising agent

A substance that brings about oxidation, i.e., addition of oxygen or removal of hydrogen, is called oxidising agent.

Reducing agent

A substance that brings about reduction i.e., removal of oxygen or addition of hydrogen, is called reducing agent.

Isomerization reactions

The reactions in which rearrangements of atoms within molecules of a substance, takes place resulting in the formation of a new substance are known as isomerization reactions. The product formed as a result of isomerization reaction has same molecular formula as the reactant but has different molecular structure.

Corrosion:

The process of slow conversion of metals into their undesirable compounds( usually oxides) by reaction with moisture and other gases present in the atmosphere is called corrosion of metals. Corrosion of metal is an oxidation process.

Rancidity:

The food material containing fat or oil develop a disagreeable odour and taste when left exposed to warm moist air a long time. This is called rancidity. Rancidity caused due to hydrolysis and oxidation.

In order to minimize rancidity due to oxidation certain substance which prevent oxidation are added foods containing oils and fats. Such substance can be slowed down by storing of food items containers and by flushing out air with some of gas like nitrogen.

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