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Synthesis and Analysis of K3Fe(C2O4)33H2O29 November 2018CHEM 003B/QR7
2Introduction:This experiment involves the synthesis of potassium ferric oxalate, the verification of thepurity, and the composition of the product derived. In a series of three different parts, potassiumferric oxalate is made and analyzed. The amount of potassium ferric oxalate is determined usingtitration and an independent analysis is done by using a spectrophotometer to determine theconcentration of iron in the sample. The equation for the overall reaction to obtain potassiumferric oxalate is: 2FeC2O4H2O (s) + H2O2(aq) + H2C2O4(aq) + 3K2C2O4(aq)2K3Fe(C2O4)33H2O(s). However, in order for potassium ferric oxalate to be produced, ferrous oxalate must beformed. The equation for the formation of ferrous oxalate is given as: Fe(NH4)2(SO4)26H2O (aq) +H2C2O4(aq)FeC2O42H2O (s) + 2(NH4)HSO4(aq)4H2O (s). Before the concentration of iron inthe sample is determined, the iron in our product is made into a new complex using thephenanthroline molecule. The equation for the formation of the complex of iron(ii) withphenanthroline is: Fe+2+ 3C12H8N2Fe(C12H8N2)3+2. Then, iron is reduced by the hydroxylaminehydrochloride compound.The equation for the reduction of iron(iii) by hydroxylamine is: 4Fe+3+2H2NOH4Fe+2+ N2O + 4H++ H2O. The amount of oxalate ion in the sample is then determinedby titrating the solution of the product with potassium permanganate. The equation is given as:5C2O4-2+ 2MnO4-+ 16H+10CO2+ 2Mn+2+ 8H2O.Experimental:The synthesis of potassium ferric oxalate trihydrate was started by preparing ferric oxalate.This was done by adding 5 grams of Fe(NH4)2(SO4)26H2O with 5 drops of H2SO4in 15 mL ofdeionized water. Once the solid dissolved and was sufficiently mixed, 25 mL of 1M oxalic acid
3was added. The solution was clamped to a ring stand and heated using a Bunsen burner to allowthe reaction to occur. After carefully heating and mixing the solution, the reaction occurred: thesolid FeC2O42H2O was formed. The remaining liquid was then poured out and the solid was leftin the flask. The flask was placed once again on the ring stand and 20 mL of deionized water wasadded to the solid to heat it again in order to get rid of the ammonium bisulfate tetra hydrate,2(NH4)HSO44H2O. After the solution settled, the liquid was decanted from the solid. 10 mL ofsaturated potassium oxalate was then added to the solid. A solution of 20 mL of 3% H2O2wasplaced in a beaker and 8 mL of 1M of H2C2O4was placed into a graduated cylinder. The solid wasthen heated to 40°C and 20 mL of H2O2was added slowly by using a transfer pipette to allow thefull reaction to occur. When substances are added slowly to other compounds during a chemicalreaction, it reduces the chances of having side reactions and also allows the full reaction to occur.