chapter 1 Chemical reaction and equations

Physical change Ver. Chemical change

Physical change: (i) Changes related to physical properties of a substance. (ii) No new substances formed. (iii) These changes are reversible. Examples: Tearing of a paper, Conversion of ice to water, Cutting of a tree.

Chemical change: (i) Changes related to chemical properties of a substance. (ii) New substances are formed. (iii) This change is irreversible. Examples: Curdling of milk, Burning of coal, Fermentation of grape, Digestion of food, Respiration.

Chemical Reaction

Such changes in which new substances are formed , initial identity of a substance changed, and irreversible are called chemical reaction. Examples: Burning of Magnesium ribbon, Digestion of food, Corrosion of iron article.

Changes during chemical reaction:

(i) change in state,

 (ii) change in colour,

(iii) Evolution of gas,

(iv) change in temperature.

Chemical equation

The Symbolic representation of a chemical reaction in which reactants and products are shown in form of chemical formulae are known as chemical equation.

Ex. - Magnesium + Oxygen→  Magnesium oxide (word eq.)

Mg + O2→ MgO  (chemical eq.)

Balanced chemical equation : A chemical equation in which both sides reactants side and product side, number of each elements are equal called a balanced chemical equation.

Mg + O2→ 2MgO

Skeleton chemical equation - An unbalanced chemical equation is called skeleton chemical equation.

Mg + O2→ MgO

                                                      ***Full chapter notes comming soon***