Iodine (I2) is a molecule composed of two iodine atoms. It is a dark-colored solid at room temperature and can sublimate into a purple vapor when heated. Iodine is an essential element for thyroid hormone production in humans.
| IUPAC Name | Diiodine |
| Molecular Formula | I2 |
| CAS Number | 7553-56-2 |
| Synonyms | Molecular iodine, iodine molecular, iodine crystals, iodine sublimed, diatomic iodine |
| InChI | InChI=1S/I2/c1-2 |
Iodine Properties
Iodine Formula
The chemical formula for iodine is I2, which indicates that it is composed of two iodine atoms. The formula is written using the symbols for the elements and subscripts to indicate the number of atoms present. The formula for iodine is essential for determining the chemical properties of iodine and for writing chemical reactions involving iodine.
Iodine Molar Mass
The molar mass of I2 is approximately 253.81 g/mol. It is a halogen element that belongs to the same group as fluorine, chlorine, bromine, and astatine. The molar mass of I2 is calculated by adding the atomic masses of its two atoms, which are 126.90 g/mol each. I2’s molar mass plays a crucial role in determining the amount of I2 present in a given sample.
Iodine Boiling Point
The boiling point of I2 is 184.3°C, making it a solid at room temperature. When heated, I2 sublimates directly into a violet gas without passing through a liquid phase. I2’s boiling point is relatively low compared to other halogens, such as chlorine and bromine. This low boiling point allows I2 to be easily purified through sublimation.
Iodine Melting Point
I2 has a melting point of 113.7°C, which is relatively low compared to other halogens. This low melting point means that I2 can be easily melted and used in various applications, such as in photography and in the production of I2 crystals. Additionally, I2’s melting point is close to its boiling point, making it easier to purify through sublimation.
Iodine Density g/mL
I2’s density is approximately 4.93 g/mL at room temperature and pressure. This means that I2 is denser than water, which has a density of 1 g/mL. The high density of I2 makes it useful in various applications, such as in the production of organic compounds and as a contrast agent in medical imaging.
Iodine Molecular Weight
The molecular weight of I2 is calculated by adding the atomic weights of its two atoms. The atomic weight of I2 is 126.90 g/mol, which means that its molecular weight is approximately 253.81 g/mol. I2’s molecular weight is an important factor in determining its physical and chemical properties.
Iodine Structure
I2 is a diatomic molecule, which means that it is composed of two I atoms. These atoms are held together by a covalent bond, which is formed when the atoms share electrons. The bond between the two atoms is relatively weak, which is why I2 has a low melting and boiling point compared to other halogens.
| Appearance | Dark grayish-black, crystalline solid |
| Specific Gravity | 4.93 g/cm³ |
| Color | Violet (vapor), dark grayish-black (solid) |
| Odor | Pungent, suffocating |
| Molar Mass | 253.81 g/mol |
| Density | 4.93 g/cm³ |
| Melting Point | 113.7°C |
| Boiling Point | 184.3°C |
| Flash Point | Not applicable |
| Water Solubility | 0.03 g/100 mL at 20°C |
| Solubility | Soluble in organic solvents, such as ethanol, ether, and chloroform |
| Vapour Pressure | 0.4 mmHg at 25°C |
| Vapour Density | 8.7 (air = 1) |
| pKa | 10.3 |
| pH | Not applicable |
Iodine Safety and Hazards
I2 can be hazardous if not handled properly. It can cause severe irritation and burns to the skin and eyes, and can be toxic if ingested in large amounts. Inhaling I2 vapor can also cause respiratory problems. I2 should be stored in a cool, dry, and well-ventilated area, away from heat and sources of ignition. Proper personal protective equipment, such as gloves, goggles, and a respirator, should be worn when handling I2. In case of exposure, affected areas should be flushed with water and medical attention should be sought immediately. It is important to follow proper safety protocols when handling I2 to avoid any potential hazards.
| Hazard Symbols | T (Toxic), Xn (Harmful) |
| Safety Description | Keep away from heat/sparks/open flames/hot surfaces. Do not breathe dust/fume/gas/mist/vapors/spray. Wear protective gloves/clothing/eye/face protection. IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing. IF SWALLOWED: Rinse mouth. Do NOT induce vomiting. IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower. |
| UN IDs | UN 3490 (Iodine), UN 3491 (Iodine, solid) |
| HS Code | 2801.20 |
| Hazard Class | 6.1 (Toxic substances) |
| Packing Group | II |
| Toxicity | Iodine can be toxic if ingested in large amounts and can cause severe irritation and burns to the skin and eyes. Inhaling iodine vapor can also cause respiratory problems. |
Iodine Synthesis Methods
Various methods can synthesize I2.
One common method is the oxidation of iodide ions with oxidizing agents, such as chlorine or nitric acid. The Sandmeyer reaction is the name of this method.
Another method involves the reaction of ICl with potassium iodide. The Merck reaction is the name of this method.
I2 can also be obtained from seaweed, which is a natural source of I2. The process involves harvesting and burning seaweed to extract I2 from the ash. The Calvert-Lewin reaction is the name of this method.
The reaction between hydrogen iodide and hydrogen peroxide can synthesize I2. Dowd process is the name of this method.
Another method involves the reaction of iodide and phosphorus, which produces phosphorus triiodide and red phosphorus. The phosphorus triiodide undergoes hydrolysis to produce I2.
There are several other methods for synthesizing I2, including the reaction of iodide with potassium hydroxide, the reaction of iodide and sulfuric acid, and the electrolysis of iodide solutions. The choice of method depends on the specific application and the availability of raw materials.
Iodine Uses
I2 has a wide range of uses in various industries and applications. Here are some of the most common uses of I2:
- Medicine: Used in medicine as an antiseptic, disinfectant, and sterilizing agent. It also treats thyroid disorders, such as goiter and hyperthyroidism.
- Photography: To produce a light-sensitive material for photography, manufacturers utilize I2 in the creation of silver iodide.
- Agriculture: Used as a soil nutrient to promote plant growth and prevent iodine deficiency in livestock.
- Food Industry: To prevent iodine deficiency, people add I2 as a dietary supplement to salt and other foods.
- Water Treatment: Used as a water disinfectant and to remove impurities from water.
- Chemical Industry: Used in the production of various chemicals, such as polymers, dyes, and pharmaceuticals.
- Analytical Chemistry: Used as a reagent in analytical chemistry to detect the presence of starch, lipids, and other compounds.
- Nuclear Energy: Nuclear medicine and cancer treatment utilize I-131.
- Scientific Research: Also used in scientific research to study various chemical and biological processes.
Questions:
Q: Is iodine a metal?
A: No, I2 is not a metal. It is a nonmetal.
Q: How many valence electrons does iodine have?
A: Iodine has 7 valence electrons.
Q: What is iodine?
A: I2 is a chemical element with the symbol I and atomic number 53. It is a nonmetal that is essential for human health and has various industrial and scientific applications.
Q: What is Iodine used for?
A: I2 has a wide range of uses, including as an antiseptic, disinfectant, dietary supplement, water treatment agent, soil nutrient, and in the production of various chemicals, pharmaceuticals, and polymers.
Q: Is I2 polar or nonpolar?
A: I2 (iodine) is a nonpolar molecule.
Q: What is the average rate of formation of i2?
A: The average rate of formation of I2 depends on the specific reaction and conditions involved, and would need to be calculated experimentally or through theoretical analysis.
Q: What is I2?
A: I2 is the chemical formula for iodine, a nonmetallic element that is a member of the halogen group on the periodic table. It is a dark purple solid at room temperature and a halogen with a variety of industrial and medical applications.