3.1.7 Oxidation, Reduction and Redox

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Created by
Haroon Azad

Cards (43)

  • Reduction is the gain of electrons.
  • Oxidation is the loss of electrons.
  • Oxidation and reduction occur simultaneously in a reaction because one species loses electrons which are donated and gained by another species. Therefore they are known as redox reactions.
  • Oxidation state of an element is 0.
  • Oxidation states in a neutral compound add up to 0.
  • Oxidation states in a charged compound add up to the total charge.
  • Hydrogen has an oxidation state of +1
  • Oxygen has an oxidation state of -2
  • All halogens have an oxidation state of -1
  • Group 1 metals have an oxidation state of +1
  • An oxidising agent accepts electrons from the species that is being oxidised. Therefore it gains electrons and is reduced. This is seen as a reduction in oxidation number.
  • A reducing agent donates electrons to the species being reduced. Therefore it loses electrons and is oxidised. This is seen as an increase in oxidation number.
  • Half Equations
  • The oxidation of C in C is 0
  • The oxidation of Fe in Fe3+ is +3
  • The oxidation state of Fe in Fe2+ is +2
  • The oxidation state of O in O2- is -2.
  • The oxidation state of He in He is 0.
  • The oxidation state of Al in Al3+ is +3.
  • Iron (II) oxide symbolised Fe2+.
  • Iron (III) symbolises Fe3+
  • FeCl2 is called potassium chloride. The oxidation state of Fe in this molecule is +2.
  • HClO4 is called Chloric (VII) acid. The oxidation state of H is +1, O is -2, and Cl is +7.
  • The oxidation state of any uncombined element is 0.
  • Group 1 metals always have a +1 oxidation state.
  • Group 2 metals always have a +2 oxidation state.
  • Fluorine always has a -1 oxidation state.
  • Hydrogen always has a +1 oxidation state except in metal hydrides where it is -1
  • Oxygen has a -2 oxidation state, except in peroxides where it is -1, and F2O where it is +2.
  • The oxidation state of Cl- is -1.
  • The oxidation state of Zn2+ is +2.
  • The oxidation state of Fe3+ is +3.
  • The more electronegative species will have a negative oxidation state.
  • Electronegativity increases across a period and decreases down a group.
  • Give the oxidation states in P2O5:
    P2: +10 P: +5
    O5: -10 P: -2
  • Give the oxidation states in SO4 2-:
    S: +8 -2 = +6
    O4: -8 O: -2
  • Oxidising agents are electron acceptors and themselves are reduced.
  • Oxidation is the process of the loss of electrons.
  • Reduction is the process of the gain of electrons.
  • Reducing agents are electron donors and are themselves oxidised.