OXIDATION
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| OXIDATION AND REDUCTION |
The process which
involves gain of oxygen or loss of hydrogen or loss of one or more electrons
(de-electronation) from an atom,ion or molecule is called oxidation e.g., Mg→Mg2++2e-
The positive
valency of an element increases by its oxidation.
Oxidation is the loss of electrons during a reaction
by a molecule, atom or ion.
Oxidation occurs when the oxidation state of a molecule, atom or ion is increased. The opposite process is called reduction, which occurs when there is a gain of electrons or the oxidation state of an atom, molecule, or ion decreases.An example of a reaction is that between hydrogen and fluorine gas to form hydrofluoric acid:
Oxidation occurs when the oxidation state of a molecule, atom or ion is increased. The opposite process is called reduction, which occurs when there is a gain of electrons or the oxidation state of an atom, molecule, or ion decreases.An example of a reaction is that between hydrogen and fluorine gas to form hydrofluoric acid:
H2 + F2 → 2 HF
In this reaction, hydrogen is being oxidized
and fluorine is being reduced. The reaction may be better understood if it is
written in terms of two half-reactions.
H2 → 2 H+ + 2 e-
F2 + 2 e- → 2 F-
REDUCTION
The process which
involves the gain of hydrogen or one or more electrons (electronation) or loss
of oxygen by an atom,ion or molecule is called reduction.e.g., S+2e- →S2-
Reduction involves
decrease in the positive valency of an element.
OXIDIZING AGENT (OXIDANT)
It is a substance which
accepts electron in the chemical reaction i.e., electron acceptors are
oxidising agent.
All the positively
charged species behave like oxidising agents.
Oxidising agents are Lewis
acids.
REDUCING AGENT (REDUCTANT)
The substance which
donates electron in a chemical reaction is called reducing agent, i.e.,
electron donors are reducing agents.
All the negatively
charged species behave like reducing agents.Reducing agents are Lewis base.
REDOX REACTIONS
The reactions which
involve oxidation and reduction as its two half-reactions,are called redox
reactions.
When the same element
is oxidation or reduced,the reaction is called disproportionation reaction.
OXIDATION STATES
It is the real or
imaginary charge which an atom appears to have in its combined states.
Oxidation state of an
element may be positive negative,zero or fractional.
RULES FOR DETERMINING OXIDATION STATE
The oxidation state of
an element in its free or uncombined state is zero.Oxidation state of O
in O2 and O3 is
zero.
Oxidation
state of hydrogen in most of its compounds is plus one (+1).
Oxidation
state of oxygen in most of its compounds is minus two (-2).
Oxidation
state of elements of IA, IIA and IIIA sub-group elements in their compounds are
+1, +2 and +3 respectively.
Oxidation
state of any ion is equal to its charge.
The
algebraic sum of the oxidation states of all elements present in polyatomic ion
is equal to the charge on the ion.
Oxygen
shows positive oxidation state in OF2
Oxidation state of
fluorine (F) is always 1.
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