Preparation of Potassium Ferric Oxalate

Introduction

Potassium Ferric Oxalate is is mostly found in form of crystal in the shaped of octahedral pattern. These crystals are found in light greenish colour. This chemical compound is derived by reacting Ferric sulphate and Barium Sulphate in presence of Oxalic acid.

What is Potassium Ferric Oxalate?

Potassium Ferric Oxalate is an inorganic chemical compound is found in the form of crystals salts. The lime green shaded crystals are produced in a laboratory by mixing of Ferric Oxalate and Barium Oxalate in presence of Oxalic acid.

Figure 1 − Potassium Ferric Oxalate

This chemical product is built with Ferric Oxalate anions $\mathrm{[Fe(C_{2}O_{4})_{3}]^{3-}}$− and Potassium Cations K+. This compound has different names like, Potassium trioxaloferrate(III) and Potassium tris(oxalato)ferrate(III). This chemical product often exists in the form of a trihydrate with the formula of $\mathrm{K_{3}[Fe(C_{2}O_{4})^{3}].3H_{2}O}$.

Aim

The experiment aims to create pure samples of Potassium Ferric Oxalate crystals from Oxalic acid dihydrate, Potassium monohydrate, and Ferric Chloride.

Theory

$\mathrm{K_{3}[Fe(C_{2}O_{4})^{3}].3H_{2}O}$ is derived by dissolving Ferric Hydroxide into the solution of Oxalic acid. It creates yellow precipitation of Ferrous Oxalate. Upon further dissolution, of Potassium oxalate monohydrate, green precipitation of Potassium Ferric Oxalate is obtained. The chemical reactions of the aforementioned aspects are given below −

$$\mathrm{FeCl_{3}\:+\:3KOH\:\rightarrow\:Fe(OH)_{3}\:+\:3KCl}$$

$$\mathrm{2Fe(OH)_{3}\:+\:3(COOH)_{2}.2H_{2}O\:\rightarrow\:Fe_{2}(C_{2}O_{4})_{3}\:+\:12H_{2}O}$$

$$\mathrm{Fe_{2}(C_{2}O_{4})_{3}\:+\:3(COOH)_{2}.H_{2}O\:\rightarrow\:2K_{3}[Fe(C_{2}O_{4})_{3}].3H_{2}O}$$

In this course of the experiment, Oxalic acid is added in excess to dissolve the Ferric Hydroxide and a complexis obtained. Alcohol is also mixed into the solution to form precipitation of complex of iron salts.

Materials required

These are the following materials required for the experiment −

• Oxalic acid Hydrate

• Ferric Chloride

• Potassium Hydroxide

• Breaker

• Conical flask

• Tripod stand

• Glass rod

• Wire Gauze

• Filter paper

• China dish

• funnel

Procedure

The procedure to be followed is mentioned as follows −

Figure 2 − Preparation of Potassium Ferric Oxalate

• A 3.5g of fresh prepared Ferric Chloride is dissolved in 10 mmol of water in a clean beaker.

• 4g of Potassium Hydroxide is required to be mixed in 50 mL of H2O in another beaker.

• Potassium Hydroxide solution is added steadily into the solution of Ferric Chloride and it is stirred thoroughly. A brown shaded Ferric Hydroxide precipitation is obtained.

• The precipitation of Ferric Hydroxide is required to be filtered using a funnel and the precipitation is further required to be washed using hot water.

• A 4g of Oxalic acid and 5.5g of Potassium Oxalate is mixed in another clean beaker. 100ml of H2O is added to it and the entire solution is stirred properly to derive a solution of Potassium Oxalate.

• The newly prepared Ferric Hydroxide precipitate is mixed with Potassium Oxalate solution slowly and the entire course is stirred constantly to make the precipitate dissolve thoroughly. The solution then exhibits green colouration.

• The solution is filtered to remove any traces of impurities.

• Then the green-coloured solution is to be transferred onto a china dish and then it is concentrated until crystals are formed.

• The china dish is placed in cold water and then it should be cooled for nearly an hour.

• Green-tinted Potassium Ferric Oxalate is obtained and then they are separated from the solution.

• The crystals are required to be washed properly using Ethyl alcohol and then it is dried inside the folds of filter paper.

• Finally, the crystals are required to be weighed to assess the yield.

Observation

Following is the observation from the experiment −

Crystal colour −	Green colour
Crystals shape −	Octahedral
Melting point −	230°C
Expected yield −	10g

Table 1 − Observation of the experiment

Precaution

Certain precautions are followed in the course of the experiment. The precautions are mentioned as follows −

• One should not concentrate on the solution too much.

• The solution should not be disturbed at all to obtain big-sized crystals during the experiment.

• The crystals are required to be washed properly to dissolve the unwanted assaults that have been formed during the experiment.

• The apparatus used in this experiment should be cleaned thoroughly before and after of the experiment.

• Safety precautions should be followed during the experiment while handing the chemical solution and the pieces of equipment.

Conclusion

Potassium Ferric Oxalate is complex chemical inorganic product. This chemical compound is derived in the form of crystals of lime green colour. The crystals show definitive traits and are obtained in octahedral structure. The Potassium Ferric Oxalate crystals always exist in trihydrate form. The experiment is conducted following several safety measures and proper procedures.

FAQs

1. What are the uses of Potassium Ferric Oxalate?

Potassium Ferric Oxalate is used in the course of photometry and actinometry. In early times, this chemical is also helpful in generating blueprints before the existence of modern pieces of machinery like inkjets and laser printers.

2. What is crystallization?

Crystallization is the process of structure orientation of atoms or the molecules into a specific structure. This process helps in deriving solid products are derived from a solution.

3. What are the traits of Ferrioxalate anions?

The anion is a transition metal complex contains +3 oxidation state of Iron and −3 of $\mathrm{C_{2}O_{4}^{3-}}$- anions acts as ligands. The solution contains salt particles are dispersed and generates Ferrioxalate anions in bright green colour.