Chemical Reaction :
A process in which one or more substances react to form new substances with new chemical identity and property.
Chemical Equation :
A chemical equation is the symbolic representation of a chemical reaction . Symbols and formulae of the reactants and products are used for the same.
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| Chemical Reaction |
Balanced chemical Equation :-
A chemical equation in which the number of atoms of each element on reactant side is equal to that of product side.Balancing of chemical equation is done to follow the law of conservation of Mass ( mass can neither be created nor be destroyed during a chemical'reaction ').
The method used for balancing chemical equations is called hit and trial method (i- e .trial) as we make trials to balance the equation by using the smallest whole number coefficient.
Balance : Fe +H2O - Fe3O4 t H2
solution-
Step 1 : check the number of atoms of each elements on the reactant and products side of the equation.
Step 2 : First of all , to balance oxygen atom we multiply H2O molecules by 4.
Fe +4(H2O) - Fe3O4 + H2
Step 3 : once again check the number of atoms of each elements on both sides.
Step 4: Balancing Hydrogen atom by multiplying H2 with 4.
Step 5 :-Balancing Fe by multiplying by 3 on LHS.
Characteristics of a chemical Reaction -
Endothermic Reactions : Reactions in which energy is absorbed.
Exothermic Reactions : Reactions in which heat is released along with the Transformation of products .(Digestion is also an exothermic).
It is not always necessary to mention the physical states and reaction conditions in a balance chemical equation . so, we can left this step until it is asked in the question.
Types Of Chemical Reactions :
Combination Reaction : In a combination reaction ,two or more reactants combine to give a single product.
Decomposition Reaction : In a decomposition reaction , a single reactant breaks down into two or more simpler products .
Thermal Decomposition : These reactions use the energy in the form of heat for decomposition of the reactant
Important Codes :
(A) Calcium carbonate on heating, decomposes to give calcium oxide and carbon dioxide.
(B) ferrous sulfate , the green color crystals Feso4 . 7H2O on heating lose water of crystallization and forms dehydrated feso4 , which on decomposition gives ferric oxide , sulfur dioxide , So2 and sulfur tri-oxide , So3 . ferric oxide is a solid, while SO2 and so3,are gases.
(C) On heating lead nitrate , it decomposes to give yellow lead monoxide,nitrogen dioxide and oxygen gas .
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