Barium sulfate ( barium sulfate ) - sulfate salt of barium . Chemical formula - BaSO 4 .
| Barium Sulphate | |
|---|---|
  | |
 | |
| General | |
| Systematic name | Barium Sulphate |
| Chem. formula | Baso 4 |
| Physical properties | |
| condition | solid |
| Molar mass | 233.43 g / mol |
| Density | 4.5 g / cm³ |
| Thermal properties | |
| T. melt. | 1580 ° C |
| T. decomp. | |
| Steam pressure | |
| Chemical properties | |
| Solubility in water | 0.0002448 g / 100 ml (20 ° C) 0.000285 g / 100 ml (30 ° C) |
| Classification | |
| Reg. CAS number | 7727-43-7 |
| PubChem | |
| Reg. EINECS number | |
| Smiles | |
| Inchi | |
| RTECS | |
| Chebi | |
| ChemSpider | |
| Security | |
| Toxicity | non toxic |
| NFPA 704 |  0 0 0 |
Content
- 1 Receiving
- 2 Properties
- 3 Chemical properties
- 4 Toxicity
- 5 Application
- 5.1 Analytical chemistry
- 5.2 X-ray contrast agent
- 5.3 Pigment filler
- 5.4 Other applications
- 6 notes
- 7 References
- 8 Literature
Getting
Barium sulfate is prepared by reacting soluble salts, barium oxide , peroxide or hydroxide with sulfuric acid or soluble sulfates :
The latter reaction is also used to produce hydrogen peroxide .
In industry, large volumes of barium sulfate are obtained from the natural mineral of heavy spar , while the feedstock is crushed and decanted .
Properties
The crystalline substance is a white powder or a transparent crystal, practically insoluble in water (solubility 0.0015 g / l at 18 ° C) and other solvents. It is found in nature in the form of the mineral barite , which is the main barium ore .
Chemical Properties
Barium sulfate is insoluble in alkalis and most acids, but soluble in chlorine water , hydrobromic and hydroiodic acids, solutions of alkali metal bicarbonates [2] .
It reacts with concentrated sulfuric acid, which converts insoluble sulfate to highly soluble barium hydrosulfate :
When calcined with coal or coke, sulfate is reduced to sulfide :
At temperatures above 1600 ° C, it decomposes:
Toxicity
Barium sulfate due to its low solubility in water is not a toxic substance for the body, unlike all soluble salts of barium, and therefore it can be used as a radiopaque substance.
Application
Analytical Chemistry
In analytical chemistry, barium sulfate is used as a good gravimetric form for the determination of sulfate ions and barium ions in a gravimetric analysis .
X-ray contrast substance
It is often used in X-ray studies of the gastrointestinal tract as a radiopaque substance , since heavy barium atoms absorb X-rays well . Although all soluble barium salts are toxic, barium sulfate is practically insoluble in water (and in hydrochloric acid , which is contained in the gastric juice ), therefore it is non-toxic. For radiographic examination of the digestive organs, the patient takes a suspension of barium sulfate (“barite porridge”) with a barium content of 58.7%.
Pigment Filler
Barium sulfate is one of the constituent mixtures used as white pigments:
- A mixture of barium sulfate with zinc sulfide , obtained by the interaction of solutions of barium sulfide and zinc sulfate , is lithopone .
- Fine-crystalline barium sulfate, obtained by precipitation of sodium sulfate from a solution of barium sulfide, is Blanc fix ( French Blanc fixe ).
It is used as an adhesive paint, as it is insoluble in organic solvents. These whitewash are cheaper than lead ones , in contrast to them they are not toxic and do not darken from hydrogen sulfide .
Other Applications
Barium sulfate is used for various industrial purposes:
- As a filler for photo and writing paper, for linoleum and for some varnish-and-paint materials. See, for example, baritage .
- Like a white filler for plastics .
- In photometry: for coloring photometric balls
- In the electrochemical industry in the manufacture of lead batteries as an expander of the active mass of the negative electrode.
- In the manufacture of glass etching pastes.
- In the manufacture of certain refractory materials .
- X-ray protector (barium plaster of X-ray cabinets).
- Adding Lego products to ensure radiopacity in case a child swallows a part (this was an experiment that ended unsuccessfully in 1996 due to reduced strength of parts and toxicity of industrial grade barium sulfate). [3]
- As the main component of tsimmerit - coating armor of German tanks and self-propelled guns during the Second World War.
- In the form of barite concentrate when drilling wells to weight clay drilling fluids .
Notes
- ↑ 1 2 http://www.cdc.gov/niosh/npg/npgd0047.html
- ↑ N.S. Frumina, N.N. Goryunova, S.N. Eremenko. Analytical chemistry of barium. - Moscow: Science, 1977.
- ↑ Peter Eio, president of Lego Systems, Inc. To the Editor // The New England Journal of Medicine : pdf. - Massachusetts Medical Society, 1996. - Vol. 334 , no. 6 . - P. 407 . - ISSN 0028-4793 .
Links
Literature
- Textbook of General Chemistry Nekrasov B.V. 1981, in 2 volumes.