Lub cev muaj zog
Calcium carbonate yog ib qho zoo, dawb crystalline hmoov uas tsis qab thiab tsw. Nws muaj nyob rau hauv ob qho tib si amorphous thiab crystalline cov ntaub ntawv. Cov ntaub ntawv crystalline muaj xws li orthorhombic thiab hexagonal systems (anhydrous calcium carbonate zoo li tsis muaj xim orthorhombic crystals, thaum calcium carbonate hexahydrate zoo li tsis muaj xim monoclinic crystals [3]); Cov muaju yog columnar lossis rhombohedral hauv cov duab, nrog qhov ntom ntawm 2.93 g / cm³. Nws melting point yog 1339℃(decomposition tshwm sim ntawm 825℃thiab 896.6 degree), thiab lub melting point yog 1289℃ntawm ib tug siab ntawm 10.7 MPa. Nws yog insoluble zoo nyob rau hauv dej-txawm hais tias nws dissolves nyob rau hauv dej uas muaj ammonium ntsev los yog ferric oxide- thiab yog insoluble nyob rau hauv cawv.
Molecular Structure
Nws cov qauv siv lead ua belongs rau orthorhombic system. Txhua chav calcium carbonate muaj ib qho carbon atom thiab peb oxygen atoms, nrog rau txhua oxygen atom bonded rau calcium ion.
Calcium carbonate yog tsim los ntawm calcium ions thiab carbonate ions tuav ua ke los ntawm ionic bonds, thaum lub hauv paus qauv ntawm cov carbonate ion nta covalent carbon -oxygen bonds. Cov carbonate ion suav nrog sp² hybridization; lub hauv paus carbon atom siv peb hybrid orbitals thiab ib p-orbital.Raws li tus qauv VSEPR, nws yog cais raws li ib tug AY3- hom molecule nrog ib tug zoo tagnrho trigonal planar geometry, featuring peb C-O bonds teem nyob rau hauv ib tug trigonal planar configuration. Tsis tas li ntawd, nws muaj ib qho delocalized p-p pi-bond system uas muaj plaub lub orbitals thiab rau electrons [5]. Nyob rau hauv cov khoom siv lead ua, calcium carbonate units tau teem rau hauv ib txheej txheej txheej thaum uas tig mus rau lub -axis thiab c-axis. Cov khaubncaws sab nraud povtseg yog sib txuas ntawm coplanar oxygen atoms, tsim cov qauv peb sab. Cov txheej txheem txheej txheem no imparts siab stability thiab hardness rau calcium carbonate.
Chemical Properties
1. Calcium carbonate decomposes rau hauv calcium oxide thiab carbon dioxide ntawm 825-896.6℃. (Cov khoom lag luam ntawm CO₂):
2. Calcium carbonate reacts nrog dilute acids (xws li dilute acetic acid, dilute hydrochloric acid, dilute nitric acid, thiab lwm yam) kom effervesce thiab yaj. Cov tshuaj tiv thaiv tawm cov pa roj carbon dioxide, ua rau nws cov tshuaj tiv thaiv exothermic. Piv txwv li, nws reacts nrog dilute hydrochloric acid los tsim calcium chloride, dej, thiab carbon dioxide (laboratory zus tau tej cov CO₂):
3. Tshaj tawm cov pa roj carbon dioxide ntau dhau rau hauv dej sib xyaw nrog CaCO₃ yuav tsim cov tshuaj calcium bicarbonate. Calcium carbonate reacts nrog cov kua roj carbonic acid (cov dej nag) los tsim cov calcium bicarbonate. Kev hla CO₂ mus rau hauv huab cua lim dej yuav ua rau cov nag lossis daus ploj. Lub hauv paus ntsiab lus qab cov phenomena yog:
4. Anhydrous calcium carbonate (ib qho dawb, tsis muaj ntxhiab, tsis yog - cov tshuaj lom neeg cov hmoov, lub teeb calcium carbonate) rhuab mus rau 1000K hloov mus ua calcite (trigonal crystal system, hnyav calcium carbonate).