- A redox titration is a volumetric method that relies on the oxidation of the analyte (substance to be analysed).
- The titrant (solution of known concentration) is often an oxidising agent.
- At the equivalence point E(forward) = E(reverse), or, ΔE(cell) = 0
- If the redox reaction does not produce a well-defined colour change at the equivalence point, an indicator should be used in the titration.
- The redox titration curve is a plot of Electrode Potential (volts) vs volume of titrant or analyte.
- Write a balanced half equation for the oxidation reaction.
- Write a balanced half equation for the reduction reaction.
- Add the oxidation and reduction half equations together to give a balanced redox reaction equation.
- Extract all the relevant information from the question.
- Check the data for consistency, for example, concentrations are often given in M or mol L-1 but volumes are often given in mL. You will need to convert the mL to L for consistency. The easiest way to do this is to multiply the volume in mL x 10-3 (enter the volume in mL into your calculator, then click "EXP", then enter -3 and the conversion is done!).
- Calculate the moles of reactant (titrant) (n) for which you have both volume (V) and concentration (molarity, c): n = c x V
- From the redox reaction equation find the mole ratio of known reactant (titrant) : unkown reactant (analyte)
- Calculate moles of unknown reactant (analyte) using this mole ratio.
- From the volume (V) of the unknown reactant (analyte) and its calculated moles (n), calculate its concentration ( molarity, c): c = n ÷ V
Examples of Redox Titration Calculations
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