月: 2023年1月

What Is Potassium Iodate?

Potassium iodate is a type of iodate salt with the chemical formula KIO3.

It is a colorless crystal that is soluble in water but insoluble in ethanol. It is stable at room temperature and decomposes into potassium iodide (KI) and oxygen when heated.

Potassium iodate is produced by reacting iodine with potassium hydroxide or by electrolyzing a potassium iodide solution. It is used in the coloring experiment of the “iodo-starch reaction” in chemistry, together with sodium thiosulfate and other substances.

Uses of Potassium Iodate

Potassium iodate is a strong oxidant and is used as an oxidant in chemical analysis, such as iodine reduction titration.

In other medical applications, it is used as a prophylactic for radiation damage and as a treatment for thyroid dysfunction due to iodine deficiency.

In overseas food products, it is added to powdered milk and salt as a dietary supplement to prevent iodine deficiency. In Japan, it is used as a feed additive to supplement nutritional components (iodine and potassium) in feed for industrial animals such as cattle, pigs, and chickens.

What Is Potassium Iodate?

Potassium iodate, with the chemical formula HIO₃, is noted for its CAS number 7782-68-5. This relatively strong acid demonstrates significant oxidizing power and can be crystallized, distinguishing it from other halide oxoacids.

Uses of Potassium Iodate

Employed as a medical astringent, disinfectant, and analytical reagent, potassium iodate’s stability in the air facilitates its handling. Its oxidative properties make it useful in analytical chemistry for titrating various iodine compounds and determining mercury and lead levels. It’s also utilized in X-ray film development and as a crystal nucleus for artificial rainfall.

Properties of Potassium Iodate

Appearing as a white crystal or powder, potassium iodate has a molecular weight of 175.91 and melts at 110°C. It’s highly soluble in water, showcasing its strength as an acid with a density of 4.62 g/mL and a pKa of 0.75.

Types of Potassium Iodate

Available as a reagent for research and as an industrial fine chemical, potassium iodate is offered in various quantities suitable for both laboratory and factory applications.

Other Information on Potassium Iodate

1. Synthesis of Potassium Iodate

Produced through the oxidation of iodine by several agents or by dissolving diiodine pentoxide in water, potassium iodate’s synthesis methods highlight its reactive nature.

2. Chemical Reaction of Potassium Iodate

In solution, it dissociates to iodate ions, acting as a potent oxidant in acidic solutions but less so in basic ones. Its reactivity with various substances necessitates careful storage away from light and incompatible materials.

3. Contrast With Other Oxoacids

While similar oxoacids like chloric and bromic acid cannot be isolated, potassium iodate stands out for its ability to be crystallized. Its existence alongside other iodine oxoacids of varying oxidation states further underscores its unique chemical properties.

4. Iodic Acid Salts

Its salts, including ammonium, potassium, and sodium iodates, are recognized for their hazardous nature, necessitating careful handling.

5. Potassium Iodate Hazard Information

As an oxidizing solid, potassium iodate poses risks of skin corrosion and irritation, classified under GHS and regulated for its hazardous and toxic nature.

What Is Copper Iodide?

Copper iodide is an odorless, inorganic compound, typically appearing as a white, light brown, or light gray powder or mass. Its chemical formula is CuI, with a molecular weight of 190.45, and it is designated under CAS No.: 7681-65-4.

Notable physical and chemical properties of copper iodide include a melting point of 605°C and a boiling point of 1,336°C. Copper iodide is slightly soluble in nitric acid or a mixture of nitric and hydrochloric acids, but is almost insoluble in water and ethanol. It is classified as a hazardous substance.

Uses of Copper Iodide

Copper iodide is utilized as a raw material in various fields, including catalysts, electronic materials, resin modifiers, and pharmaceuticals. In the electronics industry, it is recognized as a material for inorganic P-type semiconductors.

Semiconductors are classified into two types: N-type, where electrons are the primary charge carriers, and P-type, where holes (the absence of an electron in a lattice structure) act as charge carriers. In P-type semiconductors, holes appear to move similarly to electrons. Both organic and inorganic semiconductors are developed under this classification. Copper iodide’s excellent properties make it a suitable material for inorganic P-type semiconductors.

What Is Silver Iodide?

Silver iodide, with the formula AgI, occurs naturally as iodargyrite or miersite and is produced synthetically by reacting potassium iodide with silver nitrate. Classified as toxic by the GHS, it requires careful handling due to its reproductive, organ-specific, and systemic toxicity.

Uses of Silver Iodide

Employed in X-ray films, photographic emulsions, conductive glass, and notably for artificial rainfall due to its ice-like crystal lattice, silver iodide capitalizes on its photoreactive properties and similarity to ice and snow crystals for various technological and environmental applications.

Properties of Silver Iodide

Appearing as pale yellow crystals, silver iodide turns black upon light exposure. It boasts a melting point of 552°C and is notably insoluble in water but dissolves in specific solutions like concentrated nitric acid and potassium cyanide. Its unique crystal structure mimics ice, aiding in cloud seeding for rain induction.

Structure of Silver Iodide

As a silver halide, it has a molecular weight of 234.77 g/mol and exhibits polymorphism, with three known solid forms that change with temperature. Its dense crystal structure contributes to its insolubility and chemical properties.

Other Information on Silver Iodide

1. Formation of Silver Iodide Complexes

Though insoluble in water, silver iodide forms soluble complexes with alkali metal cyanides, iodides, and thiosulfates, but not with weak complexing agents like ammonia, reflecting its covalent bond characteristics and low solubility.

2. Solubility of Silver Iodide

With the lowest solubility product among silver halides, its interactions are governed by the HSAB theory, emphasizing the soft nature of both Ag⁺ and I⁻ ions and the covalent aspect of the Ag-I bond.

What Is Lithium Iodide?

Lithium iodide, with the chemical formula LiI, is an inorganic compound and an iodide of lithium. It appears as a white to light yellowish-brown crystalline substance.

It is produced through reactions involving lithium carbonate and hydroiodic acid or by introducing hydrogen iodide gas into a lithium carbonate slurry.

Uses of Lithium Iodide

1. Catalyst

Used as a catalyst in acetic acid production, lithium iodide helps control the formation of hydrogen iodide in the reaction medium.

2. Batteries

In lithium batteries, lithium iodide serves as an inorganic solid electrolyte, enhancing battery safety through its self-healing properties. This makes it especially valuable in pacemakers.

3. Other Uses

Its applications extend to absorption refrigerators, dye-sensitized solar cells, electronic materials, and neutron-detection phosphors.

Properties of Lithium Iodide

With a molecular weight of 133.85 and a melting point of 446°C, lithium iodide is soluble in water and ethanol, deliquescent, and may alter under light exposure. It is stable under normal conditions but can decompose into hazardous halides and metal oxides.

Other Information on Lithium Iodide

1. Handling Methods

Recommended safety measures include local exhaust ventilation, safety showers, and protective gear to prevent dust exposure. Eating, drinking, and smoking should be avoided during handling.

2. First Aid Measures

First aid measures include seeking fresh air for inhalation exposure, washing with soap and water for skin contact, flushing eyes with water, and rinsing the mouth if swallowed. Immediate medical attention is advised if symptoms persist.

3. Fire Precautions

In case of fire, use appropriate extinguishing media and wear protective equipment due to potential toxic fumes.

4. Storage Methods

Store in a tightly closed, light-shielded container in a cool environment, preferably refrigerated and away from direct sunlight and moisture.

5. Crystal Structure

Lithium iodide has a NaCl-type structure, contributing to its use in pacemaker batteries since 1972 due to its ion conductivity and polarization properties.

What Is Methyl Iodide?

Figure 1. Basic Information on Methyl Iodide

Methyl iodide, a monoiodide of methane, is known for its CAS number 74-88-4 and MITI number 2-42. Classified as a “deleterious substance” under various laws, it is recognized for its mutagenic properties and requires careful handling due to its designation under safety laws with a controlled concentration of 2 ppm.

Uses of Methyl Iodide

Primarily used as a fumigant and in controlling bacterial and fungal diseases in agriculture, methyl iodide’s applications extend to medical treatments for iodine deficiency and as a scintillation detector in radiation detection. Its role in livestock feed highlights its importance as an essential nutrient.

1. Medical Care

It addresses iodine deficiency, preventing goiter and hypothyroidism, and acts as a thyroid-blocking agent during nuclear incidents.

2. Scintillation Detection

Methyl iodide serves as a scintillator material, fluorescing upon radiation exposure to detect gamma rays.

3. Animal Nutrition

As a crucial feed supplement, it supports thyroid function and health in livestock.

Properties of Methyl Iodide

This colorless to brown liquid is noted for its high toxicity and characteristic odor, with a melting point of -66.45°C and a boiling point of 42.43°C. It shows excellent solubility in organic solvents and water, but decomposes in light, requiring storage in dark, sealed containers.

Other Information on Methyl Iodide

1. Reactions With Methyl Iodide

Figure 2. Reaction Using Methyl Iodide

As a precursor in Grignard reactions and a methylating agent in S_N2 reactions, methyl iodide’s versatility is showcased in the synthesis of various organic compounds.

2. Methyl Iodide as a Methylating Agent

Despite its comparative expense, methyl iodide’s ease of handling and superior methylation capacity make it a preferred choice over other halides in organic synthesis.

3. Synthesis of Methyl Iodide

Figure 3. Synthesis of Methyl Iodide

Produced through the reaction of methanol with iodine and red phosphorus, methyl iodide can be purified by column chromatography using silica gel or alumina or synthesized in high yield through the reaction of potassium iodide with dimethyl sulfate and calcium carbonate.

What Is Sodium Iodide?

Sodium iodide, an odorless white crystalline powder or granules, is known for its chemical formula NaI and molecular weight of 149.89. With a melting point of 661°C, it’s highly soluble in water and ethanol. 

Uses of Sodium Iodide

Employed in the synthesis of organoiodine compounds through the Finkelstein reaction, sodium iodide’s applications extend to scintillation radiation detection and addressing iodine deficiency. It’s crucial in medical treatments, scintillation detection, and as an animal feed nutrient.

1. Medical Care

Addressing iodine deficiency, sodium iodide is vital for preventing goiter and hypothyroidism. It acts as a thyroid-blocking agent during nuclear incidents to prevent radioactive iodine absorption.

2. Scintillation Detection

As a scintillator, sodium iodide detects gamma radiation through fluorescence, making it invaluable in gamma-ray detection.

3. Animal Nutrition

As an essential nutrient, sodium iodide is incorporated into livestock feed to support thyroid function and overall health.

Properties of Sodium Iodide

This white crystalline solid has a density of 3.67 g/cm³ and dissolves readily in water, offering a salty taste. Hygroscopic, it degrades upon exposure to air, necessitating sealed storage. Its high refractive index and fluorescence under radiation underscore its use in scintillators.

Structure of Sodium Iodide

The ionic compound exhibits a face-centered cubic crystal structure, with sodium cations surrounded by six iodide anions and vice versa, mirroring the structure of cesium iodide.

Other Information on Sodium Iodide

How Sodium Iodide Is Produced

Produced through direct, metathesis, and solid-state reactions, the predominant method involves reacting sodium hydroxide or sodium carbonate with iodine, yielding sodium iodide alongside water or carbon dioxide.

The chemical reactions: NaOH + HI → NaI + H2O
Na2CO3 + HI → NaI + H2O + CO2

Alternative production methods include electrolysis and the reaction of metallic sodium with iodine, though less commonly employed.