Carbonates


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.

Carbonates

 

salts of carbonic acid H2CO3.. There exist normal carbonates with a CO32− anion (for example, K2CO3), acid carbonates (hydrocarbonates or bicarbonates) with an HCO 3− anion (for example, KHC0 3), and basic carbonates [for example, Cu2 (OH)2CO3, the mineral malachite]. Only the normal carbonates of alkali metals, ammonium, and thallium are soluble in water. These solutions exhibit an alkaline reaction owing to the considerable degree of hydrolysis that occurs. Calcium, strontium, barium, and lead (divalent) normal carbonates are poorly soluble. Acid carbonates dissolve readily in water. As a rule, carbonates decompose upon heating (CaCO3 = CaO + CO 2), even before reaching the melting point; carbonates of alkali metals and thallium are exceptions. Hydrocarbonates are converted into normal carbonates (2NaHC03 = Na 2CO3 + H 2O + CO2) upon heating. Strong acids effect the decomposition of normal and acid carbonates with the liberation of CO2(K2CO3 + H 2SO4 = K 2SO4 + H2O +CO2).

Normal carbonates are widely distributed in nature and constitute one of the groups of minerals. Certain natural, normal, and basic carbonates are extremely valuable metallic ores, for example, carbonates of zinc, lead, copper, iron, and manganese. Nonmetallic raw materials, such as limestone CaCO3, magnesite MgCO3, and witherite BaCO3, are used in construction, in the manufacture of refractory materials, in the chemical industry, and for other purposes. Soda (Na2CO3 and NaHC0 3) and, to a lesser degree, potash K2CO3 prepared from synthetic carbon-ates are widely used in technology. Hydrocarbonates fulfill avery important physiological role as buffers.

References in periodicals archive ?
Caption: Raw feed for HuberCrete Prime, Preferred or Extra Fine gradations at Huber Carbonates' flagship limestone mine and processing mill, Marble Hill, Ga.
London, United Kingdom, Nov 7, 2013 - (ABN Newswire) - Baobab Resources Plc (LON:BAO) ('Baobab' or the 'Company') is pleased to provide further information regarding the recently discovered sequence of carbonate rocks located within 5km of the Company's Tenge/Ruoni resource block and proposed pig iron and ferro-vanadium operation.
Santi C, Certini G, D'Acqui LP (2006) Direct determination of organic carbon by dry combustion in soils with carbonates. Communications in Soil Science and Plant Analysis" 37, 155-162.
Although majority of the oil traps in the North Sea and some other places in the world are found in sand stone reservoirs, carbonate reservoirs also form large oil traps across the globe.
The Imperial team is developing simulations of carbonate reservoirs to see how C[O.sub.2] reacts with the rock when it is injected underground in Qatar.
"The presence of carbonates along with hydrothermal silicate minerals indicates that a hydrothermal system existed in the presence of CO2 deep in the Martian crust.
Acknowledgements: Thanks to all of our students in ABC: Art, Business and Chemistry who helped make and use the cobalt carbonates, and to Mary Ann Willits, our science technician, whose support was invaluable in completing this project.
Since 2000, consumption of low-calorie carbonates in Europe has increased by a third and the latest figures confirm their growing popularity.
Mineral fillers include products with less than 0.1% free crystalline silica, surface-treated calcium carbonates in particle sizes as small as 0.04 micron average present unique thickening and reinforcing opportunities.
Therefore, Mars's atmosphere had to be nearly sulfur-free before carbonates could form.
As the calculation results indicate, the increase in heating value due to non-dissociation of carbonates and sulphur binding makes 1.1-1.3% of oil-shale lower heating value and can thus, if extreme precision is not required, not be taken into account.
The uncoated mechanical sector has stepped up its efforts in evaluating ground and precipitated carbonates and carbonate/clay blends.