The molarities of the solutions are not given in this lab. This is intentional. As a teacher, it is your responsibility to thoroughly research the safety factors and respective molarities of reagents required for the completion of this lab.
Ethanedioic acid can be used to remove rust from steel. It also exists in two forms, anhydrous H2C2O4 and hydrated H2C2O4.2H2O. A redox titration can be used to deduce which form of ethanedioic acid is present in the rust remover.
A standard solution of KMnO4 is used to titrate against the ‘unknown’ rust remover. The unknown form (hydrated or anhydrous) of the rust remover will be prepared by the teacher.
Half equations for the reactions of ethanedioic acid and the manganate plus an overall equation can be deduced.
Using the titration values, the mole ratio from the overall equation and the concentration of potassium permanganate, the concentration of the unknown acid can be calculated.
If the teacher supplies the mass of acid used to make up the known volume of rust remover, the student can calculate the Mr of the acid using the calculated concentration of ethanedioc acid and the given mass of acid.
The Mr can be compared to both the anhydrous and hydrated forms of the acid