Introduction
These are the salts of carbonic acid. The anions are represented as:
- Carbonate ion trioxocarbonate (IV) : CO32-
- Bicarbonate ion or hydrogen trioxocarbonates: HCO3–
These anions are formed from carbonic acid, H2CO3 as follows:
H2CO3 <——-> HCO3– + H+ <——–> CO32- + H+
COMPOUNDS CONTAINING TRIOXOCARBONATE (IV) OR HYDROGEN TRIOXOCARBONATE (IV) ANIONS
Usually metal ions with bigger atomic size form stable trioxoxcarbonate (IV) and hydrogen trioxocarbonate (IV). Some of the hydrogen trioxocarbonate (IV) can only be detected in aqueous medium. Some important trioxocarbonate (IV) and hydrogen trioxocarbonate (IV) are listed below:
| Trioxocarbonate (IV) & Hydrogen trioxocarbonate(IV) | |||
| Group | compound | General formula | Examples |
| Group 1 (alkali metals) | carbonates | M2CO3 | Li2CO3, Na2CO3, K2CO3 etc., |
| bicarbonates | MHCO3 | LiHCO3, NaHCO3, KHCO3 etc., | |
| Group 2 (alkaline earth metals) | carbonates | MCO3 | MgCO3, CaCO3, BaCO3 etc., |
| bicarbonates | M(HCO3)2 | Mg(HCO3)2, Ca(HCO3)2 etc., | |
| p-block elements | carbonates | _ | Tl2CO3 and PbCO3 |
| Transition elements | carbonates | _ | ZnCO3, CuCO3, Ag2CO3, FeCO3 etc.,. |
OCCURRENCE
There are several carbonate minerals present in the nature. A few of them are listed below.
| Carbonate minerals | |
| Formula | Name of the mineral |
| Na2CO3 | Soda ash or Natrite |
| CaCO3 | Lime stone or Calcite or Aragonite or Chalk |
| MgCO3 | Magnesite |
| CaCO3.MgCO3 | Dolomite |
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