•Redox reactions are one of largest groups of chemical reactions.
•Redox = reduction & oxidation.
•Redox = reduction & oxidation.
•Reduction & Oxidation occur simultaneously.
•Examples:
(1) C3H8 + 5O2 → 3CO2 + 4 H20
**propane, C3H8, gains oxygen (loses hydrogen) to form CO2
**Oxygen, O2 gains hydrogen to form H20
(2) Mg + Cl2 → MgCl2 is a redox reaction.
But there is no oxygen or hydrogen involved in this reaction. We need to look for another method for showing that this is a redox reaction.
Electron transfer of redox reactions
•Oxidation is a loss of electrons.
•Reduction is a gain of electrons.
•Redox reactions involve the transfer of electrons from one reactant to another.
O I L R I G
•Example:
Combustion of magnesium in oxygen to form magnesium oxide (ionic compound)
2Mg (s) + O2 (g) → 2MgO (s)
•Mg → Mg 2+ + 2e- (oxidation)
•O2 + 4e- → 2O ^2- (reduction)
•Electrons lost by magnesium are accepted by oxygen.
In any redox reaction:
•The oxidant is the reactant which causes oxidation and is itself reduced.
•The reductant is the reactant which causes reduction and is itself oxidised.
For the reaction between Mg and O2:
•Magnesium is the reductant.
•Oxygen is the oxidant.
Summary of a typical redox reaction.
•Reactions:
•Oxidation is a loss of electrons.
•Reduction is a gain of electrons
•Reactants:
•Oxidant undergoes reduction.
•Reductant undergoes oxidation.
•Examples:
(1) C3H8 + 5O2 → 3CO2 + 4 H20
**propane, C3H8, gains oxygen (loses hydrogen) to form CO2
**Oxygen, O2 gains hydrogen to form H20
(2) Mg + Cl2 → MgCl2 is a redox reaction.
But there is no oxygen or hydrogen involved in this reaction. We need to look for another method for showing that this is a redox reaction.
Electron transfer of redox reactions
•Oxidation is a loss of electrons.
•Reduction is a gain of electrons.
•Redox reactions involve the transfer of electrons from one reactant to another.
O I L R I G
•Example:
Combustion of magnesium in oxygen to form magnesium oxide (ionic compound)
2Mg (s) + O2 (g) → 2MgO (s)
•Mg → Mg 2+ + 2e- (oxidation)
•O2 + 4e- → 2O ^2- (reduction)
•Electrons lost by magnesium are accepted by oxygen.
In any redox reaction:
•The oxidant is the reactant which causes oxidation and is itself reduced.
•The reductant is the reactant which causes reduction and is itself oxidised.
For the reaction between Mg and O2:
•Magnesium is the reductant.
•Oxygen is the oxidant.
Summary of a typical redox reaction.
•Reactions:
•Oxidation is a loss of electrons.
•Reduction is a gain of electrons
•Reactants:
•Oxidant undergoes reduction.
•Reductant undergoes oxidation.