7. oxidisation, reduction and redox reactions

• What acronym helps to remember the concepts of oxidation and reduction?

  Oil rig
• What does oxidation refer to in terms of electrons?

  Loss of electrons
• What does reduction refer to in terms of electrons?

  Gain of electrons
• What type of reaction involves both oxidation and reduction?

  Redox reaction
• In the reaction of calcium with oxygen, what happens to calcium?

  Calcium is oxidized by losing electrons
• What is the charge of calcium after it loses electrons in the reaction?

  Ca2+
• What happens to oxygen in the reaction with calcium?

  Oxygen is reduced by gaining electrons
• What is a reducing agent?

  A substance that loses electrons
• In the reaction with calcium, what role does calcium play?

  Calcium is the reducing agent
• What is an oxidizing agent?

  A substance that gains electrons
• In the reaction with calcium, what role does oxygen play?

  Oxygen is the oxidizing agent
• What are the key rules for assigning oxidation numbers?

  1. Uncombined elements: always 0
  2. Ions: oxidation number equals charge
  3. Group 1: always +1
  4. Group 2: always +2
  5. Aluminium: always +3
  6. Hydrogen: +1 except in hydrides (-1)
  7. Chlorine: -1 except with fluorine/oxygen
  8. Fluorine: always -1
  9. Oxygen: -2 except in peroxides (-1)
• What is the oxidation number of uncombined elements?

  Always zero
• What is the oxidation number of calcium in calcium oxide?

  +2
• What is the oxidation number of hydrogen in most compounds?

  +1
• What is the oxidation number of hydrogen in hydrides?

  -1
• What is the oxidation number of chlorine in KCl?

  -1
• What is the oxidation number of oxygen in most compounds?

  -2
• What is the oxidation number of oxygen in peroxides?


  -1
• What is the oxidation number of oxygen in OF2?

  +2
• How do you determine the oxidation state of sulfur in H2SO4?

  +6
• How do you determine the oxidation state of sulfur in SO4 2-?

  +6
• What is the oxidation state of iron in Fe2O3?

  +3
• What is the oxidation state of iron in FeO?

  +2
• What is the oxidation state of vanadium in V2O5?

  +5
• What is the oxidation state of vanadium in VO2?

  +4
• How do transition metals differ in oxidation states compared to other elements?

  They have variable oxidation states
• What is the importance of balancing oxidation states in a reaction?

  To ensure charge neutrality
• What is the overall charge of a neutral molecule?

  Zero
• What is the oxidation state of nitrogen in N2?

  0
• What is the oxidation state of carbon in CO2?

  +4
• What is the oxidation state of manganese in MnO4–?

  +7
• What is the oxidation state of chromium in CrO4 2-?

  +6
• What is the oxidation state of cobalt in CoCl2?

  +2
• What is the oxidation state of copper in CuSO4?

  +2
• What is the oxidation state of silver in AgNO3?

  +1
• What is the oxidation state of lithium in Li2O?

  +1
• What is the oxidation state of sodium in Na2O?

  +1
• What is the oxidation state of potassium in K2O?

  +1
• What is the oxidation state of magnesium in MgO?

  +2