Carbonates


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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 ?
This report is the result of Canadean's extensive market research covering the Carbonates market in West Europe.
Moderate growth is projected for the forecast period reflecting a mild economy improvement and higher spending on carbonates, although facing stronger competition from flavoured bottled water and powder concentrates.
Product coverage: Cola Carbonates, Non-Cola Carbonates.
3] group in aragonite is identical to that in the rhombohedral carbonates [2].
Given how much carbonate these fish can produce, the findings also clearly have major implications for our understanding of different sources and sinks of carbonate sediment in the oceans, and some exciting implications for understanding where much of the mud in limestones and chalks may derive from,' said the study's lead author, Professor Chris Perry of Manchester Metropolitan University.
Imperial College London is conducting research on a $70 million project to store carbon dioxide in carbonate rocks in the Middle East.
Consumers have been turning away from carbonates on the grounds of content, switching instead to more natural alternatives such as water, juice or juice drinks.
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Premium grades of highly pure, low-iron, platy talcs, high-purity calcium carbonates, phlogopite micas, and ground white barium sulfate for high-density compounds.
So if the Red Planet and the Blue Planet were so similar as children, why isn't the adult Mars as full of carbonates as the adult Earth?
The heat effect caused by decomposition of carbonates, if carbonates dissociate completely, is 3.
The uncoated mechanical sector has stepped up its efforts in evaluating ground and precipitated carbonates and carbonate/clay blends.