Potassium iodide (KI) is a chemical compound used to prevent the absorption of radioactive iodine by the thyroid gland. It is effective when taken before or shortly after exposure to radioactive iodine.
| IUPAC name | potassium iodide |
| Molecular formula | KI |
| CAS number | 7681-11-0 |
| Synonyms | kaliumiodid, potassium monoiodide, K iodide, KI |
| InChI | InChI=1S/HI.K/h1H;/q;+1/p-1 |
Potassium Iodide Properties
Potassium Iodide Formula
The formula for potassium iodide is KI. This formula represents the simplest ratio of potassium and iodine atoms in the compound. The formula for potassium iodide is used in calculating the amount of the compound needed in various applications, as well as in determining its molecular weight and other properties.
Potassium Iodide Molar Mass
KI has a molar mass of approximately 166.0028 g/mol. This value is calculated by adding the atomic weights of K and I in the compound, which are 39.0983 g/mol and 126.9045 g/mol respectively. The molar mass of KI is important in determining the amount of the compound needed in a given reaction or application.
Potassium Iodide Boiling Point
The boiling point of KI is 1,330 °C (2,426 °F). This high boiling point is due to the strong ionic bonding between potassium and iodine atoms in the compound. KI is used in high-temperature applications due to its ability to withstand extreme heat without decomposing or losing its effectiveness.
Potassium Iodide Melting Point
The melting point of KI is 681 °C (1,258 °F). This relatively low melting point makes KI easy to handle and process at moderate temperatures. The compound is commonly used in the production of photographic film, pharmaceuticals, and in nuclear medicine due to its low melting point.
Potassium Iodide Density g/mL
The density of KI is 3.123 g/mL. This value is higher than that of water, making KI relatively heavy and dense. The density of KI is important in determining its solubility in various solvents and in its applications as a radiation protectant.
Potassium Iodide Molecular Weight
The molecular weight of KI is approximately 166.0028 g/mol. This value represents the sum of the atomic weights of the constituent elements in the compound. The molecular weight of KI is important in determining its properties and in calculating its concentration in solutions.
Potassium Iodide Structure
KI has a simple crystal structure, consisting of a face-centered cubic arrangement of K+ ions and I- ions. The ions are held together by strong ionic bonds, which give the compound its high melting and boiling points. The crystal structure of KI is important in understanding its physical and chemical properties.
| Appearance | white crystalline powder |
| Specific gravity | 3.123 |
| Color | colorless to white |
| Odor | odorless |
| Molar mass | 166.0028 g/mol |
| Density | 3.123 g/mL |
| Melting point | 681 °C (1,258 °F) |
| Boiling point | 1,330 °C (2,426 °F) |
| Flash point | not applicable |
| Water solubility | 128 g/100 mL (20 °C) |
| Solubility | soluble in ethanol, acetone, and glycerol |
| Vapour pressure | negligible |
| Vapour density | not applicable |
| pKa | 10.8 |
| pH | 6.0 – 9.0 (5% solution) |
Potassium Iodide Safety and Hazards
KI is generally considered safe when used appropriately. However, like all chemicals, it can pose hazards if mishandled or used improperly. KI can irritate the skin, eyes, and respiratory system, and prolonged exposure may lead to more serious health effects. It is also toxic if ingested in large amounts. Proper handling, storage, and disposal procedures should be followed when working with KI. In addition, personal protective equipment, such as gloves and eye protection, should be worn when handling the compound.
| Hazard symbols | Xi |
| Safety description | Avoid breathing dust/fume/gas/mist/vapours/spray. Wear protective gloves/eye protection/face protection. IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. |
| UN IDs | UN 3077 |
| HS code | 28276000 |
| Hazard class | 9 – Miscellaneous hazardous materials |
| Packing group | III |
| Toxicity | LD50 (oral, rat) > 10,000 mg/kg |
Potassium Iodide Synthesis Methods
There are several methods for synthesizing KI, but one of the most common involves the reaction of iodine with potassium hydroxide or potassium carbonate in water. The equation for this reaction is:
I2 + 2KOH → KI + KIO3 + H2O
The process produces KI, potassium iodate, and water as byproducts. Heating the mixture decomposes the potassium iodate and leaves behind pure KI.
Another method for synthesizing KI involves the reaction of iodine with potassium bisulfite in water. This reaction produces KI along with sulfur dioxide gas as a byproduct. The equation for this reaction is:
I2 + 2KHSO3 → 2KI + 2SO2 + H2O
The resulting KI can be purified by recrystallization from hot water.
Seaweed contains high levels of iodine, which chemists can use to obtain KI. The process involves burning seaweed to produce ash, dissolving the ash in water, and treating it with potassium hydroxide to produce KI.
Potassium Iodide Uses
Here are some common uses of KI:
- Radiation protection: Used to protect the thyroid gland from radiation in the event of a nuclear accident or attack. It works by saturating the thyroid gland with non-radioactive iodine, which prevents the uptake of radioactive iodine isotopes.
- Medicinal purposes: Used to treat thyroid conditions such as hyperthyroidism and goiter. Also used as a nutritional supplement to prevent iodine deficiency.
- Photography: Used as a component in photographic emulsions.
- Analytical chemistry: Used in analytical chemistry to determine the concentration of oxidizing agents in a sample.
- Organic chemistry: Used in organic chemistry reactions as a source of iodine.
- Animal nutrition: Used as a feed additive for livestock to prevent iodine deficiency and improve overall health.
- Starch detection: Used as a reagent for detecting the presence of starch in solutions.
- Reducing agent: Act as a reducing agent in certain chemical reactions.
Questions:
Q: Where can I buy potassium iodide near me?
A: You can buy KI at many pharmacies, health food stores, and online retailers. It is often sold as a nutritional supplement or as a radiation protective agent.
Q: Which group of clients should not receive potassium iodide?
A: Individuals with certain thyroid conditions or allergies to iodine should not take KI. It is important to consult with a healthcare provider before taking any supplements or medications.
Q: Which solution is 6.0 percent (m/m) potassium iodide (KI) in water?
A: A 6.0 percent (m/m) solution of KI in water means that 6.0 grams of KI are dissolved in 100 grams of water.
Q: What is potassium iodide?
A: KI is a chemical compound consisting of potassium and iodine. Its chemical formula is KI.
Q: Is KI ionic or covalent?
A: Potassium iodide (KI) is an ionic compound. It is formed by the electrostatic attraction between positively charged potassium ions and negatively charged iodide ions.
Q: Is KI soluble in water?
A: Yes, potassium iodide is highly soluble in water. At room temperature, approximately 140 grams of KI can be dissolved in 100 milliliters of water.
Q: What is KI in chemistry?
A: In chemistry, KI is the chemical formula for potassium iodide, a compound used in various applications including radiation protection, medicinal purposes, and analytical chemistry.