Chemical Reactions and Equations
Chemical Reactions and Equations
Define
the reactant and product in chemical reaction.
The
substances taking part in chemical reaction are called reactants, whereas the
substances formed as a result of a chemical reaction by formation of new bonds
are called products.
1)
What is the importance of a chemical equation?
A chemical equation can convey the
following information.
1) Reactants and products involved in the
reaction.
2) Symbols and formulae of all substances
involved in the reaction.
3) Relative number of reactants and product participating in the
reaction.
4) Relative masses of reactants and products.
5) Physical states of reactants and products
2)
Physical states of reactants and products are mentioned while writing a
chemical equation.
1)
To make a chemical
equation more informative, the physical states of the reactants and products
are mentioned along with their chemical formulae.
2) The gaseous, liquid,
aqueous and solid states of reactants and products are represented by the
notations (g), (l), (aq) and (s) respectively.
3)
The word aqueous (aq)
is written if the reactant or product is present as a solution in water.
3)
Displacement reaction:- The reaction in which
the place of the ion of a less reactive
element in a compound is taken by another more reactive element by formation of
its own ions, is called displacement reaction.
6)
Exothermic
reaction:- The
reactions in which heat is released are called Exothermic reaction.
Types of chemical reactions
Chemical
reactions are classified into the following four types in accordance with the
nature and the number of the reactants and the products.
1)
Combination reaction: - When two or more
reactants combine in a reaction to form a single product, it is called a
combination reaction.
2) Decomposition reaction:- The chemical reaction in
which two or more products are formed from a single reactant is called
‘‘Decomposition reaction”.
3)
Displacement reaction:- The reaction in which
the place of the ion of a less reactive
element in a compound is taken by another more reactive element by formation of
its own ions, is called displacement reaction.
4) Double displacement reaction:- The reaction in which the ions in the reactants are exchanged to form a precipitate are called double displacement reactions.
5) Endothermic reactions:- The reactions in which heat is absorbed are called endothermic reactions. The reactants absorb heat for form products
6)
Exothermic
reaction:- The
reactions in which heat is released are called Exothermic reaction.
7) Oxidation:-The chemical reaction in which a reactant combines with oxygen or loses hydrogen to form the product is called oxidation reaction.
8) Reduction: - The chemical reactions in which reactants gain hydrogen are called ‘reduction’ reactions. Similarly, the reaction in which a reactant loses oxygen to form the product is also called reduction reaction.
9) Redox reaction:- The chemical reactions in which oxidation and reduction takes place simultaneously are called redox reactions. "Red" stands for reduction and "ox" stands for oxidation.
10) Neutralization: The chemical reaction in which an acid and alkali (base) react together to form salt and water is called neutralization. The resulting solution is neither acidic nor basic but is neutral. This reaction is known as neutralization reaction.
What is corrosion?
The
slow process of decay or destruction of a metal due to the effect of air, moisture,
acids, base or other chemicals on it is called corrosion or rusting of iron.
Its chemical formula is Fe2O3. H2O.
Explain the term rancidity.
Rancidity is a chemical process in which edible oils or fats get
oxidized over a period of time and become inedible (unfit for human
consumption) is called rancidity.
When oil or ghee is left aside for a long time or fried
food is left aside for a long time it undergoes air oxidation and becomes
rancid
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