redox Flashcards
1
Q
oxidation
A
- gain of oxygen
- loss of electrons
- increase in oxidation number
2
Q
reduction
A
- loss of oxygen
- gain of electrons
- decrease in oxidation number
3
Q
disproportionation
A
- when a single species is simultaneously both oxidised and reduced
- use OS to work this out
4
Q
oxidising agents
A
- give oxygen to another substance
- remove electrons from another substance (so are reduced themselves)
- strongest oxidising agents are found in group 7
5
Q
reducing agents
A
- remove oxygen from another substance
- give electrons to another substance (so are oxidised themselves)
- strongest reducing agents are found in group 1
6
Q
oxidation states (OS)
A
- oxidation/reduction in covalent compounds
- instead of true loss/gain of electrons, ‘degree of sharing’ of electrons changes
7
Q
Rules for assigning OS
A
- OS of an atom in its elemental state = 0
- sum of the OS of all the atoms in a compound = 0
- OS of an ion = the charge on the ion (Cl- = -1)
- OS of a group ion = the charge on the ion
- OS of an oxygen atom in a compound = −2, except in peroxides it = -1 / when with fluorine it = +2
- OS of a hydrogen atom in a compound = +1, except in metal hydrides it = -1
8
Q
using OS to spot oxidation/reduction
A
- If the OS of an element increases, then it has been oxidised.
- If the OS of an element decreases, then it has been reduced.
9
Q
water OS
A
- oxygen = -2
- hydrogen = +1