Iron (III) hydroxide is a compound formed by iron reacting with water. It is commonly used in pharmaceuticals, water treatment, and as a pigment in paints.
| IUPAC Name | Iron(III) hydroxide |
| Molecular Formula | Fe(OH)₃ |
| CAS Number | 20344-49-4 |
| Synonyms | Ferric hydroxide, Iron trihydroxide, Ferric hydrate, Iron(III) oxyhydroxide |
| InChI | InChI=1S/Fe.3H2O/h;3*1H2/q+3;;;/p-3 |
Iron (III) Hydroxide Properties
Iron (III) Hydroxide Formula
The formula for Iron(III) hydroxide is Fe(OH)₃. It indicates that each molecule of Fe(OH)₃ consists of one Fe atom bonded to three OH ions.
Iron (III) Hydroxide Molar Mass
The molar mass of Fe(OH)₃ can be calculated by adding up the atomic masses of its constituent elements. Iron has a molar mass of 55.845 g/mol, and each hydroxide ion (OH) has a molar mass of 17.007 g/mol. Therefore, the molar mass of Fe(OH)₃ is approximately 106.867 g/mol.
Iron (III) Hydroxide Boiling Point
Fe(OH)₃ does not have a well-defined boiling point since it decomposes before reaching its boiling point. Instead, it undergoes thermal decomposition to form iron(III) oxide and water when heated.
Iron (III) Hydroxide Melting Point
Fe(OH)₃ also decomposes upon heating and does not have a distinct melting point. It transforms into iron(III) oxide and water at elevated temperatures.
Iron (III) Hydroxide Density g/mL
The density of Fe(OH)₃ depends on various factors such as its physical state (solid or solution) and concentration. The density of a solid form of Fe(OH)₃ is around 3.4 g/mL.
Iron(III) Hydroxide Molecular Weight
The molecular weight of Fe(OH)₃ is calculated by summing the atomic weights of its constituent atoms. The molecular weight of Fe(OH)₃ is approximately 106.867 g/mol.
Iron (III) Hydroxide Structure
Fe(OH)₃ adopts a trigonal structure, where one iron atom is surrounded by three hydroxide ions. The iron atom acts as the central atom, and the hydroxide ions are bonded to it through ionic bonds.
Iron (III) Hydroxide Solubility
Fe(OH)₃ has limited solubility in water. It forms a precipitate when dissolved in water, and the solubility depends on various factors such as temperature, pH, and the presence of other ions. The solubility of Fe(OH)₃ increases in acidic conditions.
| Appearance | Brown solid |
| Specific Gravity | 3.4 |
| Color | Brown |
| Odor | Odorless |
| Molar Mass | 106.867 g/mol |
| Density | 3.4 g/mL |
| Melting Point | Decomposes |
| Boiling Point | Decomposes |
| Flash Point | Not applicable |
| Water Solubility | Insoluble |
| Solubility | Insoluble. Depends on factors such as temperature, pH, and the presence of other ions |
| Vapour Pressure | Negligible |
| Vapour Density | Not applicable |
| pKa | Not applicable |
| pH | Approximately 5-7 |
Iron (III) Hydroxide Safety and Hazards
Fe(OH)₃ poses certain safety considerations and hazards. It is generally considered to be of low toxicity. However, ingestion or inhalation of large amounts may cause gastrointestinal irritation and respiratory discomfort. It is important to avoid eye and skin contact, as it may cause irritation. In case of contact, rinse affected areas thoroughly with water. When handling Fe(OH)₃, it is advisable to wear appropriate protective equipment, such as gloves and goggles, to minimize the risk of exposure. Proper ventilation should be ensured to prevent the accumulation of dust. Additionally, it is crucial to follow safety guidelines and handle Fe(OH)₃ with caution to minimize potential risks.
| Hazard Symbols | None |
| Safety Description | – Avoid eye and skin contact <br> – Wear protective equipment <br> – Ensure proper ventilation |
| UN IDs | Not applicable |
| HS Code | 2821.10.0000 |
| Hazard Class | Not classified |
| Packing Group | Not applicable |
| Toxicity | Low toxicity |
Iron (III) Hydroxide Synthesis Methods
There are various methods to synthesize Fe(OH)₃. One commonly used method involves the precipitation reaction between an iron salt and a base. For instance, by adding a solution of iron chloride (FeCl₃) to a solution of sodium hydroxide (NaOH), Fe(OH)₃ can be formed. The reaction occurs as follows:
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
In another method, one can oxidize Iron(II) hydroxide to Fe(OH)₃ by exposing it to air or treating it with an oxidizing agent. The reaction occurs as follows:
4Fe(OH)₂ + O₂ → 2Fe(OH)₃
Moreover, one can prepare Fe(OH)₃ by hydrolyzing an iron salt solution. This process involves adding water to the iron salt solution, resulting in the formation of a precipitate of Fe(OH)₃. The reaction occurs as follows:
FeCl₃ + 3H₂O → Fe(OH)₃ + 3HCl
These synthesis methods offer ways to obtain Fe(OH)₃ for various applications, including pharmaceuticals, water treatment, and as a pigment in paints. It is important to follow appropriate safety precautions and handle the chemicals responsibly during the synthesis process.
Iron (III) Hydroxide Uses
Fe(OH)₃ has several applications due to its unique properties. Here are some common uses of Fe(OH)₃:
- Pharmaceutical Industry: The pharmaceutical industry utilizes Fe(OH)₃ in the production of iron supplements and medications, such as those used for treating iron-deficiency anemia.
- Water Treatment: Water treatment processes employ Fe(OH)₃ to remove contaminants and impurities. Fe(OH)₃ acts as a flocculant, aiding in the agglomeration and removal of suspended particles from water.
- Pigment in Paints: Fe(OH)₃, with its brown color, finds application as a pigment in paints, coatings, and dyes. It imparts a range of earthy tones and is particularly useful in producing ochre and sienna colors.
- Wastewater Treatment: Wastewater treatment plants utilize Fe(OH)₃ to eliminate phosphates and heavy metal contaminants from industrial wastewater.
- Catalysis: Fe(OH)₃ acts as a catalyst in various chemical reactions, including the decomposition of hydrogen peroxide and oxidation reactions.
- Adsorbent: Fe(OH)₃ serves as an adsorbent material for removing impurities, contaminants, and colorants from solutions.
- Soil Amendment: Fe(OH)₃ acts as a soil amendment to enhance soil fertility and nutrient availability. It improves the nutrient-holding capacity of the soil and provides essential iron for plant growth.
- Lab Reagent: In laboratory settings, researchers and analysts employ Fe(OH)₃ as a reagent for various analytical and research purposes, including precipitation reactions and pH adjustment.
The versatile applications of Fe(OH)₃ highlight its significance in different industries and its contribution to various processes ranging from pharmaceuticals to environmental remediation.
Questions:
Q: What is the correct formula weight of iron(III) hydroxide?
A: The correct formula weight of Fe(OH)₃ is approximately 106.867 g/mol.
Q: What is the complete ionic equation for the reaction between FeBr3 and barium hydroxide?
A: The complete ionic equation for the reaction between FeBr3 and barium hydroxide is FeBr₃ + 3Ba(OH)₂ → 3BaBr₂ + Fe(OH)₃.
Q: What mass of iron(III) hydroxide precipitate can be produced by reacting 75.0 mL?
A: To determine the mass of Fe(OH)₃ precipitate, additional information such as the concentration or molarity of the reactants is required.
Q: How to form iron(III) hydroxide?
A: Fe(OH)₃ can be formed by various methods, including precipitation reactions between iron salts and bases, oxidation of Fe(OH)2, or hydrolysis of an iron salt solution.
Q: Is iron(III) hydroxide soluble?
A: No, Fe(OH)₃ is not soluble in water. It forms a precipitate when dissolved in water.
Q: How many grams of Fe(OH)₃ contain 4.61 grams of Fe³⁺?
A: To determine the grams of Fe(OH)₃, the molar mass of Fe³⁺ and the stoichiometry of the reaction are needed.
Q: What color is Fe(OH)₃?
A: Fe(OH)₃ is typically brown in color.
Q: Is iron hydroxide a solid?
A: Yes, iron hydroxide exists as a solid.
Q: What does thermally decomposed iron hydroxide produce?
A: Thermally decomposed Fe(OH)₃ produces iron(III) oxide (Fe₂O₃) and water.
Q: Is iron hydroxide soluble in water?
A: No, iron hydroxide is not soluble in water. It forms a precipitate when mixed with water.