E2 Fe Complex Synthesis and Analysis.pdf - EXPERIMENT 2...

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2 – 1 EXPERIMENT 2 Synthesis and Analysis of Potassium Tris(oxalato)ferrate(III) Trihydrate Objectives: Synthesize a transition metal complex, potassium tris(oxalato)ferrate (III) trihydrate [K 3 Fe(C 2 O 4 ) 3 ·3H 2 O] in a two-step process Practice laboratory techniques such as decantation, recrystallization, gravity and suction filtration Determine the actual, theoretical, and percent yields of product Analyze the synthesized compound by determining the number of waters of hydration by gravimetric analysis Determine the number of oxalate ion groups coordinated to the synthesized compound by titration Introduction: A chemical synthesis is the use of one or more chemical reactions to bring about the construction of a desired chemical product or products. The reasons for carrying out a chemical synthesis are varied. It might be the production of a useful substance not found in nature (plastics, for example) or the production of a substance found in nature but difficult or expensive to isolate in large quantities, such as ammonia. Then again, it might be the desire to create a substance with new, useful properties, say, a new medication. Whatever the motivation for the synthesis, maximizing the conversion of reactants to products is always a priority. In this experiment, you will synthesize the compound potassium tris(oxalato)ferrate(III) trihydrate [K 3 Fe(C 2 O 4 ) 3 ·3H 2 O] in a two-step process. The first step involves the reaction of ferrous ammonium sulfate hexahydrate [Fe(NH 4 ) 2 (SO 4 ) 2 ·6H 2 O] with oxalic acid (H 2 C 2 O 4 ): Fe(NH 4 ) 2 (SO 4 ) 2 ·6H 2 O( s ) + H 2 C 2 O 4 ( aq ) (Pale green) FeC 2 O 4 ·2H 2 O( s ) + (NH 4 ) 2 SO 4 ( aq ) + H 2 SO 4 ( aq ) + 4H 2 O( l ) (1) (Yellow) Where applicable, the colors of reactants and products are indicated in parentheses below their molecular formula. The iron (II) oxalate dihydrate (FeC 2 O 4 ·2H 2 O) produced in the Reaction (1) will be separated from the other products by decantation. In the second step, the iron (II) oxalate dihydrate will be converted to potassium tris(oxalato)ferrate (III) trihydrate [K 3 Fe(C 2 O 4 ) 3 ·3H 2 O] through reaction with oxalic acid, hydrogen peroxide (H 2 O 2 ), and potassium oxalate (K 2 C 2 O 4 ): 2 FeC 2 O 4 ·2H 2 O( s ) + H 2 C 2 O 4 ( aq ) + H 2 O 2 ( aq ) + 3 K 2 C 2 O 4 ( aq ) (Yellow) 2 K 3 Fe(C 2 O 4 ) 3 ·3H 2 O( s ) (2) (Green)
Expt. 2: Synthesis and Analysis of Potassium Tris(oxalato)ferrate(III) Trihydrate 2 – 2 The potassium tris(oxalato)ferrate (III) trihydrate crystals then are separated from solution by vacuum filtration. Your objective is to prepare as great a yield of potassium tris(oxalato)ferrate (III) trihydrate as possible. To measure the effectiveness with which this objective is met, you will calculate the percent yield: 100 yield l theoretica ield y actual yield Percent × = (3) The theoretical yield is the calculated maximum amount of product that might be obtained under ideal conditions from the reactants. In an experiment, the theoretical yield is seldom, if ever, reached. In this experiment, the theoretical yield is the maximum number of grams of product [K 3 Fe(C 2 O 4 ) 3 ·3H 2

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