oxidation, reduction and redox equations

• what is a redox reaction?

  reduction and oxidation occurring simultaneously
• what is reduction?

  1. gain of electrons
  2. loss of oxygen
  3. gain of hydrogen
• what is oxidation?

  1. loss of electrons
  2. gain of oxygen
  3. loss of hydrogen
• what is the oxidation number?

  charge of atom that would exist if the bonding was completely ionic
• what is the oxidation state of elements in their standard state?

  0
• what is the oxidation state of simple ions?

  equal to the charge on ion
• what are exceptions to the oxidation state of simple ions?

  metal hydrides – H = -1

  peroxide ion – O = -1

  oxygen with fluorine – O = +2

  ClO - Cl = +1

  ClO2 - Cl = +3

  ClO3 - Cl = +5

  ClO4 - Cl = +7
• where are oxidation states shown in name of compounds?

  in brackets
• what is the process of writing a half equation?

  1. balance element being oxidised or reduced
  2. balance oxygen atoms by adding H2O
  3. balance hydrogen atoms by adding H+
  4. add electrons to balance out charges
• how to balance redox reaction equations?

  Combine oxidation half equation and reduction half equation

  Total number of electrons gained = total number of electrons lost
• what is a reducing agent?

  donate electrons

  it is oxidised
• what is an oxidising agent?

  except electrons

  it is reduced
• what is disproportionation?

  when an element is simultaneously oxidised and reduced
• what is an example of a disproportionation equation?

  Cl2 + H2O --> HClO + HCl