Redox Reactions
Reduction
Oxidising agent
2AG+(aq) + Cu(s) -> Cu2+(aq) + 2Ag(s)
+1 0 +2 0
Ag+ is being reduced
Cu is being oxidised
You can write a redox equation from oxidation numbers to work out what is being reduced and what is being oxidised
Formula S + HNO3 -> H2SO4 + NO2 + H2O
Oxidation Number (S) 0 +6
Oxidation Number (N) +5 +5
Balancing equations
In acid solution manganite (VII) ions, MN042-, oxidise C2O42-ions to carbon dioxide. Mn2+ is also produced in the reaction
MNO42- + C2O42 -> CO2 + Mn2+
MNO42 -> Mn2+ C2O42 -> CO2
MNO42 -> Mn2+ + 4H2O C2O42-> 2CO2
MNO42- + 4H+ -> Mn2+ + 4H2O C2O42 -> 2CO2
MNO42- + C2O42- + 6H+ -> Mn2+ + 4H2O + 2CO2
Write out half equations
Balance the oxygen
Balance the hydrogen and electrons
Reduction
- Gain of electrons
- Decrease in oxidation number
- Loss of oxygen
- Loss of electrons
- Increase in oxidation number
- Gain of oxygen
Oxidising agent
- Takes electrons from the substance being oxidised
- The oxidising agent is the substance being reduced
- Adds electrons to the substance being reduced
- The reducing agent is the substance being oxidised
2AG+(aq) + Cu(s) -> Cu2+(aq) + 2Ag(s)
+1 0 +2 0
Ag+ is being reduced
Cu is being oxidised
You can write a redox equation from oxidation numbers to work out what is being reduced and what is being oxidised
Formula S + HNO3 -> H2SO4 + NO2 + H2O
Oxidation Number (S) 0 +6
Oxidation Number (N) +5 +5
Balancing equations
In acid solution manganite (VII) ions, MN042-, oxidise C2O42-ions to carbon dioxide. Mn2+ is also produced in the reaction
MNO42- + C2O42 -> CO2 + Mn2+
MNO42 -> Mn2+ C2O42 -> CO2
MNO42 -> Mn2+ + 4H2O C2O42-> 2CO2
MNO42- + 4H+ -> Mn2+ + 4H2O C2O42 -> 2CO2
MNO42- + C2O42- + 6H+ -> Mn2+ + 4H2O + 2CO2
Write out half equations
Balance the oxygen
Balance the hydrogen and electrons