THE CONCEPT OF REDOX

A. TERMINOLOGY

Match the following phrases with the correct definitions.

OXIDATION NUMBER

OXIDATION

REDUCING AGENT
or
REDUCTANT

HALF EQUATIONS

OXIDISING AGENT
or
OXIDANT

REDOX REACTION

REDUCTION

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1.

A chemical reaction involving the transfer of electrons.

Reduction and oxidation ALWAYS occur together in a chemical reaction.

Redox reaction

2.

Reactions which show the transfer of electrons from one species to another.

Electrons are either lost or gained from a chemical species. Equations may be classified as oxidation or reduction.

Half equations

3.

The loss of electrons by a chemical species.

Shown by writing an oxidation half equation

eg. Mg → Mg2+ + 2e-  OIL (Oxidation Is Loss).
       0          +2

Oxidation

4.

The gain of electrons by a chemical species.

Shown by writing a reduction half equation.
eg. Cl2 + 2e-   → 2Cl-      RIG (Reduction Is Gain).
        0                       -1 

Reduction

5.

A substance that brings about the reduction of another chemical species, while being oxidised in the process.

ACTIVE METALS ARE GOOD REDUCING AGENTS (eg. Na, Mg, Ca and Zn)
Na → Na+ + e-        OIL                    Na is the reducing agent. It loses electrons
½Cl2 + e- → Cl-     RIG                    (ie. is oxidised) causing Cl to be reduced.
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Na + ½Cl2 → Na+Cl- or NaCl

Reductant

6.

A substance that brings about the oxidation of another chemical species, while being reduced in the process.

Na → Na+ + e-        OIL                    Cl2 is the oxidising agent. It gains electrons
½Cl2 + e- → Cl-     RIG                    (ie. is reduced) causing Na to be oxidised.
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Na + ½Cl2 → Na+Cl- or NaCl

Oxidant

7.

The “apparent” charge of an atom in a compound or ion.

The bond may be covalent. eg. CO2(g). The apparent charge on the carbon atom is +4

Oxidation number

 

Molar Mass
 

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