Karbonat

Karbonat is the term used for salts or esters of carbonic acid and for the carbonate ion CO3^2−. In chemistry, carbonates form a broad class of compounds composed of a metal cation bonded to a carbonate group. The carbonate ion is trigonal planar and exhibits resonance between three equivalent C–O bonds.

Common natural carbonates include calcium carbonate (CaCO3), sodium carbonate (Na2CO3), and magnesium carbonate (MgCO3). Carbonates occur widely in minerals such as calcite, aragonite, and dolomite, and they form important sedimentary rocks like limestone, chalk, and marble (metamorphosed limestone). Biogenic carbonates make up shells and corals.

Production and reactions: Carbonates can be produced by neutralization of carbonic acid with metal oxides or hydroxides. They decompose on heating to oxides and carbon dioxide (for example CaCO3 → CaO + CO2 at high temperatures). Reaction with acids releases CO2.

Industrial and everyday uses: Sodium carbonate is used in glassmaking, papermaking, and as a water-softening agent; calcium carbonate serves as a filler, pigment, and antacid; calcium oxide derived from carbonates is fundamental to cement production. Carbonates also appear in detergents, pharmaceuticals, and agriculture.

Environmental aspects: In natural waters, the carbonate system buffers pH. Ocean uptake of atmospheric CO2 alters carbonate equilibria, reducing carbonate ions and affecting calcifying organisms.

Safety: Carbonates are generally low-toxicity, but powder forms and acidic reactions can irritate tissues; handling should follow standard lab or industrial hygiene practices.