Saturday, 30 August 2014

Endothermic Reactions-Exothermic Reactions-Law of Conservation of Mass

ENDOTHERMIC REACTION
"All those chemical reaction in which heat is absorbed in going
from reactants to product are known as "Endothermic reactions.
"
   These reactions can not proceed without addition of heat.
   For example
2KClO3 + Heat è 2KCl + 3O2
CaCO3 + Heat è CaO + CO2
Graphical Representation
 
EXOTHERMIC REACTION
 
   All those chemical in which heat is released in going from reactant to product are known as exothermic    reactions.
   For example
3H+ N2 è 2NH3 + Heat
2SO2+O2 è 2SO3 + Heat
Graphical Representation
 
CHEMICAL REACTION
 
   A process in which chemical change in the nature and composition of substances occurs is called chemical    reaction
   For example
CaCO3 + HEATè CO2 + CaO3H2 + N2 è 2NH3
CHEMICAL EQUATION
 
   A chemical equation is a symbolic formation of chemical change in terms of symbols and formula.
CHARACTERISTICS OF A CHEMICAL EQUATION
 
   1. A chemical equation must be a representative of a chemical reaction.
   2. It should represent molar quantities.
   3. It should be balanced in terms of atoms and molecules of reactants and products.
   For example:
2SO2+O2 è 2SO3
3H2 + N2 è 2NH3
LAW OF CONVERSATION OF MASS
 
   The law of conservation of mass indicates that during any process, mass is neither created nor destroyed.
   The law was put forward by a French chemist LAVOISER in 1785.
   Law of conversation of mass states that :
  1. Mass can neither be created nor destroyed during a chemical reaction.
  2. During a chemical reaction total mass of products is equal to the total mass of reactant

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