Preparation and Analysis of an Iron Salt - Experiment 8 -...

Preparation and Analysis of an Iron Salt
Introduction:
The goal of this lab was to determine whether a specific preparation of potassium
tris (oxalato) ferrate (III) trihydrate salt is a reliable and productive method. The two
aspects of the synthesis that are to be analyzed are the yield of the salt obtained from the
reaction and the purity of the salt produced.
Experimental:
To prepare the salt, 7.5 g of Fe(NH
4
)
2
(SO
4
)
2
•6H
2
O were first weighed out on a top
loading balance and was dissolved in 25 mL of warm water, acidified with about 1 mL of
6M sulfuric acid. Next, 35 mL of a prepared oxalic acid solution were added while
stirring this solution. The solution was then cautiously heated to steaming with frequent
stirring. After a granular yellow precipitate of ferrous oxalate had formed, the supernatant
liquid was decanted trying to avoid loss of solid. The solid was then washed with 25 mL
of hot water and again decanted. 15 mL of a prepared 1.8 M potassium oxalate solution
was then added to the solution and warmed to 40˚C. 16 mL of 7.5% H
2
O
2
were then
added while stirring the solution continuously and keeping the temperature around 40˚C.
Ferric Hydroxide then formed and was dissolved by heating and adding 8 mL of oxalic
acid, followed by a drop by drop addition of 6 more mL. After a green solution appeared,
15 ml of ethanol was added to the hot solution and the solution was covered and left to
cool. The salt was then obtained by vacuum filtrating after being washed three times 5-