Redox

Redox

1. Ion Formation

   • Metals: Are oxidised and form positive ions.
   • Non-Metals: Are reduced and form negative ions.

2. Oxidation Number Rules

   • Ion: Charge on ion
   • Uncombined Element: 0
   • Combined Oxygen: -2
   • Combined Hydrogen: +1
   • Combined Fluorine: -1
   • If there is a roman numeral after an element name, that element has that oxidation number (e.g. In Iron(II) Chloride, Iron has an oxidation number of 2+).

3. Reactions

   • Metals+Acids
     • Metal is oxidised to form positive ion
     • Hydrogen in acid reduced to form hydrogen gas
     • Acid+Metal==Salt+H2
   • Half Equations
     • Show the oxidation or reduction of certain elements during a reaction.
     • e.g. Mg+Cl2==MgCl2
       • Mg==Mg(2+)+2[e(-)]
       • Cl2+2[e(-)]==2[CL(-)]

4. Definitions

   • Reduction
     • Gain of electrons
     • Decrease in oxidation number.
   • Oxidation
     • Loss of electrons
     • Increase in oxidation number.