E7- Synthesis of Potassium Tris(oxalato)ferrate(III) Trihydrate

Abstract: In this lab, the transition metal complex Tris(oxalato)ferrate(III) Trihydrate was synthesized in a two-step process. Using decantation and filtration, the complex was separated from liquid and massed to determine the mass yield of 5.717g. Using gravimetric analysis, the number of waters of hydration, 4.74, was determined.
Experimental Method: To a 200mL beaker, 4.987g of ferrous ammonium sulfate hexahydrate was added. The solid was then dissolved with 15mL of distilled water to which 5 drops of 3M sulfuric acid was added. 25mL of 1M oxalic acid was added, and the color changed from a previous blue/green to an orange color. A magnetic stirbar was added, and the solution was brought to boiling. The solution settled and the liquid was decanted twice carefully. 20mL of saturated potassium oxalate solution was added, and the solution became a darker orange. Using a thermometer, the solution was heated to 40 degrees Celsius and 20mL of 3% hydrogen peroxide was added very slowly. The solution turned reddish brown and some bubbles formed on the top. The solution was then heated to boiling, and 8mL of 1M oxalic acid was added, the first 5mL all at once and then the last 3mL very slowly. The solution became brown, so 5 more mL of oxalic acid was added and the solution turned into a bright green color. The solution settled at room temperature, and then was funneled into a specimen cup. 10mL of ethanol was added to the cup, and then placed inside of the lab desk, away from light. In the following lab period, the mass of a filter paper was massed. Using a Buchner funnel with a second piece of filter paper, the crystals in the specimen cup were filtered and air dried for 15 minutes, and then massed. A .500g portion of the crystals were put in a drying oven for an hour at 115 degrees Celsius and then dried to determine the number of moles of water per salt.

Data:
Mass of 200mL beaker
Mass of beaker and
Mass of
Mass of filter paper
Mass of filter paper and crystals
Mass of crystals formed Mass of crystal sample dried
Mass of water lost
Moles of water per mole of salt
78.170g
83.157g
4.987g
.529g
6.246g
5.717g
.500g
.087g
4.74

Discussion:

Actual yield: 5.717g
Theoretical yield: