Types of Chemical Reactions

Text-only Preview

Types of Chemical Reactions
Types of Chemical Reactions
A chemical reaction is a process that leads to the transformation of one set of chemical
substances to another. ] Chemical reactions can be either spontaneous, requiring no input of
energy, or non-spontaneous, typical y fol owing the input of some type of energy, such as
heat, light or electricity.
Classical y, chemical reactions encompass changes that strictly involve the motion of
electrons in the forming and breaking of chemical bonds between atoms, and can often be
described by a chemical equation.
The general concept of chemical reactions between atoms has been be extended to the non-
chemical reactions between entities smal er than atoms, including nuclear reactions,
radioactive decays, and reactions between elementary particles as described by quantum field
The substance (or substances) initial y involved in a chemical reaction are cal ed reactants or
Chemical reactions are usually characterized by a chemical change, and they yield one or
more products, which usually have properties different from the reactants.
Know More About :- Equilibrium Constant Expression

Page No. :- 1/4

Reactions often consist of a sequence of individual sub-steps, the so-cal ed elementary
reactions, and the information on the precise course of action is part of the reaction
Chemical reactions are described with chemical equations, which graphically present the
starting materials, end products, and sometimes intermediate products and reaction
Different chemical reactions are used in combination in chemical synthesis in order to obtain a
desired product. In biochemistry, series of chemical reactions catalyzed by enzymes form
metabolic pathways, by which syntheses and decompositions impossible under ordinary
conditions are performed within a cel .
Writing a Chemical Reaction
A chemical reaction is written with the formula of reactants on the left side, and formula of the
products formed on the right. An arrow is placed in-between the reactants and the products.
In a reaction between Hydrochloric acid (HCl) and sodium hydroxide (NaOH), the chemical
equation is written as:
HCl + NaOH H2O + NaCl
An arrow separates the reactants from the products. The arrow is usually pointed in the
direction in which it is proceeding. If a reaction is reversible, the middle arrow is shown as
double arrows:
Learn More :- Kinetic Molecular Theory of Gases

Page No. :- 2/4

Since each chemical reaction fol ows law of mass action, the moles of a particular element wil
be same throughout. If 2 moles of chlorine are reacting, 2 moles of chlorine would be present,
in any combined form in the products.
In the reaction between nitrogen and hydrogen to form ammonia, 2 moles of N2 react with 3
moles of H2 to form 2 moles of NH3. This is shown in the form of equation as:
2 N2 + 3H2
So, every chemical equation has to be solved or balanced for the moles of reactants reacting
and moles of products formed.
Limitation of a Chemical Equation
There are certain limitation of chemical equations as follows :
1. Chemical equation does not clarify the state of the substances. So (s) for solid, (l) for liquid,
(g) for gas and (vap) for vapor may be added.
2. The reaction may or may not be conclude but the equation does not reveal it.
3. Chemical equation does not give any information regarding the speed of the reaction.
4. Chemical equation does not give the concentration of the substances and in some cases,
the terms like diluted and concentrated are used.

Page No. :- 4/4


Document Outline

  • ﾿