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Based on the nature of chemical changes, reactions can be
classified into five types (i) combination reactions, (ii)
decomposition reactions, (iii) displacement reactions, (iv)
double-displacement reactions, and (v) oxidation-reduction
reactions.
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The reactions in which all the reactants and products are
present in the same phase are called homogeneous reactions
and the reactions in which reactants and products are present
in different phases are called heterogeneous reactions.
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The reactions in which heat is evolved are called exothermic
reactions and the reactions in which heat is absorbed are
called endothermic reactions.
•
The reactions that can occur in forward and reverse directions
simultaneously under same set of conditions are called reversible
reactions.
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A system is said to be in a state of equilibrium if none
of its properties changes with time.
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One mole of a gas occupies a volume of 22.7 L at STP (standard
temperature and pressure) i.e. at 273 K temperature and
1 bar pressure.
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An acid is a substance that furnishes hydrogen ions, H+;
a base is a substance that furnishes hydroxyl ions, OH–;
in its solutions and a salt is produced when an acid and
a base react with each other.
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An electrolyte conducts electric current through itself
in the molten state or through its solution. If it dissociates
completely it is known as a strong electrolyte and if it
dissociates only partially it is known as a weak electrolyte.
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pH of a neutral solution is 7, that of an acidic solution
is less than 7 and that of a basic solution is more than
7 at 250C
