CBSE Class 10science Revision Notes Chapter-01 Chemical Reaction and Equations
CBSE Class 10science Revision Notes Chapter-01 Chemical Reaction and Equations
CBSE Class 10science Revision Notes Chapter-01 Chemical Reaction and Equations
Class 10Science
Revision Notes
CHAPTER- 01
CHEMICAL REACTION AND EQUATIONS
Chemical Reaction : Whenever a chemical change occurs we can say that a chemical
reaction (permanent change) has taken place which can be expressed symbolically by a
chemical equation.
Rusting of iron.
magnesium is burnt in air to form magnesium oxide. This chemical reaction can be
represented as
Baalanced Equation : A balacned equation is one in which the number of atoms on the
reactant and product sides are equal.
Types of Reaction
I. Combination Reaction :– The reaction in which two or more substances combine to form
a new single substance.
e.g.
slaked lime is used for white washing walls. It reacts with to form
Calcium Carbonate and gives a shiny finish to the walls
heat+ light
Exothermic Reactions : Reaction in which heat is released along with the formation of
products.
eg..
eg..
II. Decomposition Reactions :The reaction in which a single substance decomposes to give
two or more substances. De composition reactions can be of three types:
DECOMPOSITION REACTIONS :-
2. .
Copper (aq)
IV. Double Displacement Reaction :The reaction in which two different atoms or group of
atoms are mutually exchanged
A white substance is formed due to above reaction. The insoluble substance i.e., is
called precipitate.
When copper is heated a black colour appears. If this CuO is reactedwith hydrogen gas then
again Cu becomes brown as reverse reaction takes place
Redox Reaction : The reaction in which one reactant gets oxidised while other gets
reduced
eg..
Rancidity :When fats and oils are oxidised they become rancidand their smell and
taste change.
Antioxidants are added to foods containing fats and oil.
A complete chemical equation represents the reactants, products and their physical
states symbolically.
A chemical equation is balanced so that the numbers of atoms of each type involved
in a chemical reaction are the same on the reactant and product sides of the equation.
Equations must always be balanced.
In a combination reaction two or more substances combine to form a new single
substance.
Decomposition reactions are opposite to combination reactions. In a decomposition
reaction, a single substance decomposes to give two or more substances.
Reactions in which heat is given out along with the products are called exothermic
reactions.
Reactions in which energy is absorbed are known as endothermic reactions.
When an element displaces another element from its compound, a displacement
reaction occurs.
Two different atoms or groups of atoms (ions) are exchanged in double displacement
reactions.
Precipitation reactions produce insoluble salts.
Reactions also involve the gain or loss of oxygen or hydrogen by substances.Oxidation
is the gain of oxygen or loss of hydrogen. Reduction is the loss of oxygenor gain of
hydrogen.