General Chemistry Laboratory
The Determination of Oxalate Ion in Ferric Oxalate
Trihydrate using Titrimetry
Learn how to perform a quantitative chemical analysis.
Learn how to perform a titration.
Learn about Oxidation-Reduction reactions.
In this laboratory exercise, we will determine the Percentage Oxalate Ion (C
) in the
Potassium Ferric Oxalate Trihydrate (K
O) sample we synthesized previously.
This will be accomplished using a technique called Titration; a type of Volumetric Analysis.
This type of analysis involves adding a Potassium Permanganate (KMnO
) solution, whose
concentration is previously determined, to a solution of the Oxalate until the reaction between
these species is complete.
By knowing the reaction stoichiometry, the volume Permanganate Ion
) solution required for complete reaction, and the concentration of the solution used, we
can quantitatively determine the mass percentage of Oxalate Ion present in our sample.
then be compared with the expected mass percentage Oxalate based on our compound's chemical
formula and therefore allow us to confirm or discount the solid we have generated is indeed the
trioxalate of Iron.
A volumetric analysis involves measuring the volume of a solution of known concentration, the
Titrant, Permanganate Ion in the present case, which is needed to completely react with an
Analyte, the Oxalate Ion of our Ferric Oxalate sample.
The titration reaction is complete when a stoichiometrically equivalent amount of titrant has been
added to the analyte and all the analyte has been consumed; a point in the titration called the
To be successful things must be arranged so that some distinct visual change
occurs in the analyte solution at the Equivalence Point.
at which this visual change
occurs is called the Endpoint of the titration.
(But, shouldn't the Endpoint be the same as the
Yes, and it is the job of the analyst to pick a visual indicator that will ensure
this is so.)
The trick in any titration is to stop adding titrant at the exact point the Endpoint is
reached because it is only at this point that a stoichiometrically correct amount of titrant has
been added to the analyte.