Chem – ELECTROCHEMISTRY
Electrochemistry is the study of the conversion of electrical energy into chemical
energy and chemical energy into electrical energy.examples: found in dry cells,
button cells or lead acid batteries.
When electric current is passed through an aqueous solution or molten salts, it
causes a chemical reaction to occur. This converts electrical energy to chemical
energy.
Oxidation and Reduction as Electron Transfer Process
Oxidation is the loss of one or more electrons by an atom or ion. Reduction is
the gain of one or more electrons by an atom or ion.
Reducing agent ( aka reductant): An atom that loses electrons and helps another
atom to get reduced. In this reaction, sodium is the reducing agent. Oxidising agent
(oxidant): A species that gains electrons and helps another species to get
oxidised.here chlorine is the oxidising agent.
Redox Reactions : 1. Oxidation and reduction always happens in same time,
independently.
A redox reaction is a reaction in which oxidation and reduction occur
simultaneously.
Oxidation Number: In simple molecules, it is easy to identify oxidation and
reduction. but In polyatomic molecules, it becomes difficult. To solve this, we use
oxidation number. Oxidation number is the apparent charge which an atom appears to
have when each pair of electrons is counted with more elecronegative atom..
Oxidation number is always assigned to an atom. It is written as a number with a +ve or
−ve sign.
,
+ve oxidation number - atom that shifts electrons away from itself.
-ve oxidation number: the more electronegative atom that gains electrons. Oxidation state
(OS) is another term used for oxidation number.
Rules for Assigning Oxidation Number- 8 rules.
Using these rules, find the oxidation number of S, N and Cl atoms in : (a) H2
SO4 (b)NO– 3 (c) ClO– 4 respectively
a. H2so4 = 1. Let the oxidation number of sulphur be x. Since the
oxidation number of O is –2. Therefore the sum of four O atoms is
equal to –8. (2x4)
2.the oxidation number of each H is +1, two H atoms have total oxidation number
of +2.
Electrochemistry is the study of the conversion of electrical energy into chemical
energy and chemical energy into electrical energy.examples: found in dry cells,
button cells or lead acid batteries.
When electric current is passed through an aqueous solution or molten salts, it
causes a chemical reaction to occur. This converts electrical energy to chemical
energy.
Oxidation and Reduction as Electron Transfer Process
Oxidation is the loss of one or more electrons by an atom or ion. Reduction is
the gain of one or more electrons by an atom or ion.
Reducing agent ( aka reductant): An atom that loses electrons and helps another
atom to get reduced. In this reaction, sodium is the reducing agent. Oxidising agent
(oxidant): A species that gains electrons and helps another species to get
oxidised.here chlorine is the oxidising agent.
Redox Reactions : 1. Oxidation and reduction always happens in same time,
independently.
A redox reaction is a reaction in which oxidation and reduction occur
simultaneously.
Oxidation Number: In simple molecules, it is easy to identify oxidation and
reduction. but In polyatomic molecules, it becomes difficult. To solve this, we use
oxidation number. Oxidation number is the apparent charge which an atom appears to
have when each pair of electrons is counted with more elecronegative atom..
Oxidation number is always assigned to an atom. It is written as a number with a +ve or
−ve sign.
,
+ve oxidation number - atom that shifts electrons away from itself.
-ve oxidation number: the more electronegative atom that gains electrons. Oxidation state
(OS) is another term used for oxidation number.
Rules for Assigning Oxidation Number- 8 rules.
Using these rules, find the oxidation number of S, N and Cl atoms in : (a) H2
SO4 (b)NO– 3 (c) ClO– 4 respectively
a. H2so4 = 1. Let the oxidation number of sulphur be x. Since the
oxidation number of O is –2. Therefore the sum of four O atoms is
equal to –8. (2x4)
2.the oxidation number of each H is +1, two H atoms have total oxidation number
of +2.
