How to Prepare Ferric Hydroxide Sol with Chemical Reaction Equation and Principle
Here, we discuss a step-by-step procedure for conducting an experiment to help you learn how to prepare ferric hydroxide sol. To understand the goal, procedure, and materials required to perform the experiment, go through the content carefully.
Aim
The aim of this experiment – to prepare ferric hydroxide sol.
Theory
A lyophobic sol is formed by ferric hydroxide. Lyophobic colloids are called compounds such as metal hydroxides or sulfides that are insoluble and do not readily have colloidal solutions for treatment with water. Ferric hydroxide sol is prepared with boiling distilled water by hydrolysis of ferric chloride.
The reaction for preparation of Fe(OH)3 sol is given below
FeCl3(aq) + 3H2O(l)→ Fe(OH)3(s) +3HCl(aq)
The hydrolysis reaction creates insoluble particles of ferric hydroxide that are agglomerated to create larger colloidal-dimensional particles. To give a positive charge to the soln particles, these particles preferentially adsorb Fe3+ ions from the solution. The Soln's stability is due to the charge on the particles of the solution. Hydrochloric acid formed during hydrolysis tends to destabilize the sol and must therefore be extracted by the dialysis process from the sol, or the sol would not be stable.
Materials Required
The apparatus and materials required for this experiment are as follows:
Glass rod
Round bottom flask
Boiling tube
Conical flask of 250 mL volume
Tripod stand
Funnel
Beaker of 250 mL volume
Burette
Wire gauze
Dropper
Burner
Wire gauze
Iron stand with clamp
Boiling tube
Distilled water
The solution of ferric chloride
Procedure
Take a 250 mL conical flask and clean it with steam.
Take the aid of the following figure to clean the conical flask by steaming out the process.
(Image will be uploaded soon)
By taking 2 g of pure ferric chloride in 100 mL of distilled water, prepare a 2% solution of ferric chloride.
Take the cleaned conical flask and add 100 mL of distilled water by steaming out the process.
On a wire gauze, boil the bath.
Drop by drop, with the aid of a dropper or desk, pour 10 mL of ferric chloride solution.
Keep stirring the mixture of boiling water continuously when adding ferric chloride solution.
Until you see a brown or deep red ferric hydroxide solution, heat the conical flask containing a combination of distilled water and ferric chloride solution.
Enable the mixture to settle at room tempurature in the conical flask.
Precautions
Due to the presence of impurities, Fe(OH)3 sol is impaired. Therefore, it is washed by steaming out a method to stop this conical flask.
It is applied drop-wise to the FeCl3 solution.
Heat the distilled water and ferric chloride solution mixture until the colour is brown or deep red.
To avoid solar destabilization, the hydrochloric acid (HCl) produced is removed by the dialysis process.
Applications of Ferric Hydroxide
In the construction industry, ferrous hydroxide products such as yellow iron oxide/iron (III) oxide hydroxide are commonly used to produce concrete products such as bricks, blocks, decorative concrete, paving stones, ready-mixed concrete, and roofing tiles. A significant contributor to the growth of residential construction is a growing population in developing countries.
Did You Know?
The rapid expansion of the construction sector would fuel the growth of the demand for ferric hydroxide. Many regional/local players sell their goods across creative distribution channels to the construction industry. On the back of the expanding construction industry in India and China, the ferrous hydroxide market in the Asia Pacific region is expected to see substantial growth.
The global ferric hydroxide market is expected to hit the US＄1 billion mark by the end of 2029, with a CAGR of 5% during 2019-2029 for healthy growth. Market geographical research shows that East Asia and North America will continue to capture about 50 percent of the global ferric hydroxide market's revenue share.
FAQs on Preparation of Ferric Hydroxide Sol by Hydrolysis Method
1. What is the preparation of ferric hydroxide sol?
The preparation of ferric hydroxide sol is the formation of a colloidal solution of Fe(OH)3 by the hydrolysis of ferric chloride in boiling water. It is commonly prepared in the laboratory by adding a dilute solution of FeCl3 to boiling distilled water.
- The reaction involved is: FeCl3(aq) + 3H2O(l) → Fe(OH)3(sol) + 3HCl(aq)
- The ferric hydroxide formed remains dispersed as a positively charged colloidal sol.
- This method is called the hydrolysis method of sol preparation.
2. How do you prepare ferric hydroxide sol by hydrolysis method?
Ferric hydroxide sol is prepared by adding dilute ferric chloride solution slowly to boiling distilled water to cause hydrolysis. The step-by-step method is:
- Boil distilled water in a clean beaker.
- Add dilute FeCl3 solution dropwise with constant stirring.
- A reddish-brown Fe(OH)3 sol is formed.
- Allow the mixture to cool and dialyse to remove excess HCl.
3. What is the chemical equation for the preparation of ferric hydroxide sol?
The balanced chemical equation for preparing ferric hydroxide sol is FeCl3(aq) + 3H2O(l) → Fe(OH)3(sol) + 3HCl(aq). In this reaction:
- FeCl3 undergoes hydrolysis in boiling water.
- Fe(OH)3 forms as a colloidal sol.
- HCl remains dissolved in the solution.
4. Why is ferric hydroxide sol positively charged?
Ferric hydroxide sol is positively charged because it preferentially adsorbs Fe3+ ions from the solution. During hydrolysis:
- Excess Fe3+ ions are present in the medium.
- These ions get adsorbed on the surface of Fe(OH)3 particles.
- This gives the colloidal particles a positive charge.
5. What is the colour of ferric hydroxide sol?
Ferric hydroxide sol is reddish-brown in colour. The colour is due to the dispersed colloidal particles of Fe(OH)3 in water.
- The intensity of colour depends on concentration.
- It appears translucent when viewed against light.
- On coagulation, a brown precipitate of Fe(OH)3 is formed.
6. What type of colloid is ferric hydroxide sol?
Ferric hydroxide sol is a lyophobic colloid of the sol type with a solid dispersed phase and liquid dispersion medium. Specifically:
- Dispersed phase: Fe(OH)3 (solid)
- Dispersion medium: Water (liquid)
- Type: Solid-in-liquid sol
7. Why is ferric chloride added to boiling water and not vice versa?
Ferric chloride is added to boiling water to ensure controlled hydrolysis and proper formation of ferric hydroxide sol. If water is added to FeCl3 solution:
- Local high concentration may cause precipitation instead of sol formation.
- Uniform dispersion of Fe(OH)3 particles may not occur.
8. How is excess electrolyte removed in the preparation of ferric hydroxide sol?
Excess electrolyte such as HCl is removed from ferric hydroxide sol by the process of dialysis. In dialysis:
- The sol is placed in a parchment or semipermeable membrane bag.
- The bag is suspended in distilled water.
- Small ions like H+ and Cl- diffuse out, while colloidal particles remain inside.
9. What happens when an electrolyte is added to ferric hydroxide sol?
When an electrolyte is added to ferric hydroxide sol, coagulation occurs due to neutralization of the positive charge on the colloidal particles. Specifically:
- Anions from the electrolyte neutralize the positively charged Fe(OH)3 particles.
- The particles aggregate and settle down.
- This follows the Hardy–Schulze rule, where higher valency ions cause faster coagulation.
10. What are the precautions in the preparation of ferric hydroxide sol?
The main precautions in the preparation of ferric hydroxide sol are to ensure controlled hydrolysis and avoid premature coagulation. Important precautions include:
- Use freshly prepared dilute FeCl3 solution.
- Add ferric chloride solution slowly to boiling distilled water.
- Stir continuously to ensure uniform dispersion.
- Use clean glassware free from electrolytes.
- Remove excess HCl by dialysis for better stability.
