CHEMICAL REACTIONS: OXIDATION AND REDUCTION...10Sia1

REDOX reactions or Oxidation and Reduction Reactions occur in two parts: Reduction and Oxidation

Reduction
In general this involves the gain of electrons or loss of oxygen. The atom, molecule or compound that gains electrons is known as the Oxidant
Oxidation
In general this involves the loss of electrons or gain of oxygen. The atom, molecule or compound that loses electrons or gains oxygen is known as the reductant

Oxidation and Reduction always occur together and there is no net change in the charge. The electrons lost by the reductant must equal the electrons gained by the oxidant, ie they must balance!

Here is a worked example:

H2 + F2 ---------------> 2HF

• the first step is to separate the equation into 2 half reactions:
• H₂ → 2 H⁺ + 2 e⁻ (the oxidation reaction)
• F₂ + 2 e⁻ → 2 F⁻ (the reduction reaction)
• When the 2 half equations are combined there is no net change in charges and the Hydrogen and Flourine Ions combine to form Hydrogen Fluorine
• 
  
  •  H₂ + F₂ → 2 H⁺ + 2 F⁻ → 2 HF 
  
  
  A flash tutorial on oxidation and reduction