Key Steps and Practical Applications of Ferric Hydroxide Sol
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 How to Prepare Ferric Hydroxide Sol: Complete Guide
1. What is the standard method for preparing ferric hydroxide sol in a school laboratory?
Ferric hydroxide sol is prepared by the hydrolysis of ferric chloride with boiling distilled water. The procedure is as follows:
Take about 100 ml of distilled water in a beaker and heat it to boiling.
Add a 2% solution of ferric chloride (FeCl₃) drop by drop into the boiling water while stirring continuously.
Continue heating until a deep reddish-brown or blood-red solution is formed. This indicates the formation of the ferric hydroxide sol.
The chemical reaction is: FeCl₃ + 3H₂O → Fe(OH)₃ (sol) + 3HCl.
2. What colour change is observed during the preparation of ferric hydroxide sol, and what does it signify?
During the preparation, the initially colourless or pale yellow ferric chloride solution transforms into a deep reddish-brown coloured solution. This distinct colour change is the primary visual evidence that insoluble Fe(OH)₃ particles have formed and aggregated into colloidal dimensions, thus creating the ferric hydroxide sol.
3. Why is the ferric hydroxide sol positively charged?
The ferric hydroxide sol is positively charged due to the preferential adsorption of ions. During the hydrolysis of ferric chloride (FeCl₃), the Fe(OH)₃ precipitate particles adsorb Fe³⁺ ions from the solution onto their surface. This creates a positive layer around each colloidal particle, resulting in an overall positive charge on the sol.
4. Is ferric hydroxide considered a strong base or an alkali?
Ferric hydroxide, Fe(OH)₃, is a weak base because it does not fully dissociate in water to produce hydroxide ions (OH⁻). Furthermore, it is not an alkali because alkalis are bases that are soluble in water. Since ferric hydroxide is insoluble in water, it is classified as a base but not an alkali.
5. What is coagulation, and which electrolyte is most effective in coagulating ferric hydroxide sol?
Coagulation is the process of destabilising a colloid, causing the particles to aggregate and settle down as a precipitate. Since ferric hydroxide sol is positively charged, it is coagulated by negative ions (anions). According to the Hardy-Schulze rule, the coagulating power of an ion increases with the magnitude of its charge. Therefore, an electrolyte with a highly charged anion, such as potassium ferrocyanide (K₄[Fe(CN)₆]) which provides the [Fe(CN)₆]⁴⁻ ion, is most effective.
6. How is ferric hydroxide sol, a lyophobic colloid, different from a lyophilic colloid like starch sol?
Ferric hydroxide sol (lyophobic) and starch sol (lyophilic) differ in several key aspects:
Interaction: Fe(OH)₃ particles have little affinity for the dispersion medium (water), making it lyophobic (solvent-hating). Starch particles have a strong affinity for water, making them lyophilic (solvent-loving).
Stability: Lyophobic sols are less stable and easily coagulated by electrolytes. Lyophilic sols are much more stable and require higher concentrations of electrolytes to coagulate.
Reversibility: Fe(OH)₃ sol is an irreversible colloid. Once precipitated, it cannot be easily returned to the sol state. Starch sol is reversible; the sol can be reformed by simply mixing the precipitate with the dispersion medium.
7. What is the chemical formula used to represent a colloidal particle of ferric hydroxide sol?
The formula for a colloidal particle of ferric hydroxide sol represents the core particle and the adsorbed charge. It is written as [Fe(OH)₃]Fe³⁺. This notation indicates that the solid ferric hydroxide, Fe(OH)₃, forms the core, and it has preferentially adsorbed ferric ions, Fe³⁺, on its surface, giving it a positive charge.
