C10: Oxidation and Reduction (5088 COMBINED CHEMISTRY)

CHAPTER 10 OXIDATION DEFINITIONS: - Gain of oxygen - Loss of hydrogen - Loss of electrons - Increase in oxidation state REDUCTION DEFINITIONS: - Loss of oxygen - Gain of hydrogen - Gain of electrons - Decrease in oxidation state E.G: Fe2O3 + 3CO —> 2Fe + 3CO2 - Fe is reduced but CO is oxidised.

OXIDATION STATES RULE 0: Atoms of the same element, such as: - Single atoms; - Molecules of an element; and - Metallic elements OXIDATION STATE: 0 RULE 1: (ALL ELEMENTS) a) Group 1 elements in their compounds (Na, K, etc.) OXIDATION STATE: +1 b) Group 2 elements in their compounds (Mg, Ca, etc.) OXIDATION STATE: +2 RULE 2: (SPECIAL NON-METALS) a) Fluorine in its compounds OXIDATION STATE: -1 b) Hydrogen in its compounds OXIDATION STATE: +1 c) Oxygen in its compounds OXIDATION STATE: -2

RULE 3: (GROUPS 13 TO 17) — Elements from Groups 13 to 17 in their compounds > often based on the most common valency a) Metallic elements b) Non-metallic elements and metalloids RULE 4: (GROUPS 3 TO 12) - Elements from Groups 3 to 12 in their compounds, and elements with their proton numbers 57 to 71 or 89 to 103 OXIDATION STATE: ALWAYS POSITIVE!

OXIDISING AND REDUCING AGENTS OXIDISING AGENTS can: - Oxidise another substance - Increase the oxidation state of an element in another substance - Gain electrons from the other substance Thus, an oxidising agent causes oxidation while being reduced itself. E.G: oxygen, chlorine, potassium manganate (VII ). REDUCING AGENTS can: - Reduce another substance - Decrease the oxidation state of an element in another substance - Lose electrons from the other substance Thus, a reducing agent causes reduction while being oxidised itself. E.G: hydrogen, reactive metals (K, Na, etc.), carbon and potassium iodide.