Potassium bromide CAS 7758-02-3 is an inorganic substance with the chemical formula KBr and a relative molecular weight of 119.00. Colorless crystal or white powder, with a strong salty taste, turning yellow when exposed to light. Slightly hygroscopic. 1g is dissolved in 1.5ml of water, and the aqueous solution is neutral. The relative density is 2.75 (25 ℃). Melting point 730 ℃. Boiling point 1435 ℃. Irritating. Mainly used for spectral analysis, droplet analysis to determine copper and silver, polarographic analysis of indium, cadmium, and arsenic, developer.

Chinese Name: Potassium Bromide

Foreign name: Potassium bromide

Alias: bromide salt of potato

Chemical formula: KBr

Molecular weight: 119.0023

CAS login number: 7758-02-3

EINECS login number: 231-830-3

Melting point: 734 ℃

Boiling point: 1435 ℃

Water solubility: soluble in water

Density: 2.75 g/cm ³

Appearance: Colorless crystal or white powder

Application: Used in the production of silver bromide paper, also as an analytical reagent, and as a sedative in medicine

Physical and chemical properties

physical property

Molar mass: 119.01g/mol

Appearance: White powder

Density: 2.75g/cm3 (solid)

Melting point: 734 ℃ (1007K)

Boiling point: 1435 ℃ (1708K)

Solubility in water: 53.5g/100ml (0 ℃)

Colorless cubic crystal. Odorless, salty and slightly bitter in taste. Easy to turn yellow when exposed to light, slightly hygroscopic. Soluble in water (with a solubility of 102g/100ml of water at 100 ℃) and glycerol, slightly soluble in ethanol and ether. The aqueous solution is neutral. Its bromine ions can be replaced by fluorine and chlorine. Reacting with sulfuric acid can generate hydrogen bromide. React with silver nitrate to form yellow silver bromide precipitate.

chemical reaction

Potassium bromide is a typical ionic compound that is completely ionized and neutral when dissolved in water. Commonly used to provide bromine ions – the following important reactions can generate silver bromide for photography:

KBr (aq)+AgNO3 (aq) → AgBr (s)+KNO3 (aq)

Bromine ion Br – in aqueous solution can form complexes with some metal halides, such as:

2 KBr (aq)+CuBr2 (aq) → K2 [CuBr4] (aq)

The traditional preparation method is the iron bromine method: first, excessive bromine is used to react with iron filings in water to generate hexahydrate octabromo triferric oxide (Fe3Br8 · 16H2O), and then it reacts with boiling hot potassium carbonate solution to filter out the precipitate of ferric oxide and concentrate and crystallize to obtain:

4 K2CO3+Fe3Br8 → 8 KBr+Fe3O4+4 CO2 ↑

Application Field Editing Broadcast

1. The photosensitive material industry is used in the manufacturing of photosensitive films, developers, film thickeners, toners, and color photo bleaching agents;

2. Medically used as a sedative for nerves (tribromide tablets);

3. In addition, it is also used for chemical analysis reagents, spectral and infrared transmission, making special soaps, as well as carving, lithography, and other aspects;

4. It is also used as an analytical reagent.

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