Redox Reactions Flashcards
Oxidation
Gain O2
Lose H
Lose e-
Increase in oxidation number
Reduction
Lose O2
Gain H
Gain e-
Decrease in oxidation number
Oxidising agents
Non-metals
More reactive non-metals = more likely to accept e-s, so more positive electrode potentials
Reducing agents
Metals, reactive ones have greatest tendency to donate e-s, therefore their half-cells have most -ve electrode potentials
Uncombined element oxidation number
0
Combined oxygen oxidation number
-2
Combined hydrogen oxidation number
+1
Simple ion oxidation number
Ion’s charge
Combined fluorine oxidation number
-1
Standard electrode potential
E.m.f of half- cell compared to an H half-cell
H half-cell e.m.f
0V
Overall cell reaction calculation
1) calculate difference between half cell values
2) reverse more negative half-equation
3) add half-equations together
Redox reaction predictions
- stronger reducing agent with more negative half-cell is on right side of reaction
- stronger oxidising agent with more positive half-cell is on left side of reaction
Ionic concentration changes
Still affects equilibrium as per Le Chatelier’s principle
Reaction likeliness?
Depends on:
S.E.P must be in aqueous equilibria
Larger difference between half-cells, more likely reaction
If difference is <0.4V, reaction is unlikely to be completed
