To find the initial and final oxidation states of a species using a titration: 1. Find the moles of the known reactant and electrons transferred 2. Calculate the moles of electrons transferred per mole of the unknown species to get the change in oxidation state 3. A common mistake is thinking the number of moles of electrons transferred is equal to the coefficient in the half-reaction, when it is actually the number of electrons transferred per mole of reactants.

1. Redox
FAQs

2. Redox
If given an unfamiliar species, e.g. [Co(NH3)6]2+,
how do I know what can it oxidise/ reduce to?
Look for the species in data booklet.

3. Redox
How to find initial/ final O.S. of a species using
titration?
1. Find the amount (moles) of the known reactant.
2. Find moles of electrons transferred.
3. Find moles of electrons transferred per mole of
unknown species = change in O.S.

4. Redox
How to find initial/ final O.S. of a species using
titration?
Common Mistake:
For the half equation: 2H+ + 2e– H2
If the no. of moles of H+ = 1
no. of moles of e– transferred = 1
NOT 2 since 2H+ takes in 2e–

5. Redox
How to find initial/ final O.S. of a species using
titration?
Faster Method (For MCQs)
• Find the reacting ratio between the two redox reagents.
• Ratio x no. of electrons transferred should be the same
for both.
Fe2+ MnO4–
nratio 4 1
e– 1 ?
product 4 4