Calcium carbonate

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   Calcium carbonate   
Names: calcium carbonate

Formula: CaCO3
SMILES: C(=O)([O-])[O-].[Ca+2]
Molar mass: 100.086 g/mol
Density: 2.74 g/cm3 (calcite)
1.77 g/cm3 (aragonite)
Crystal system: rhombohedral (calcite)
a=6.36 Å, b=6.36 Å, c=6.36 Åα=46.1°, β=46.1°, γ=46.1°
orthorhombic (aragonite)
a=5.7394 Å, b=4.9616 Å, c=7.97 Åα=90°, β=90°, γ=90°
hexagonal (vaterite)
a=4.9915 Å, b=4.9915 Å, c=17.088 Åα=90°, β=90°, γ=120°

Color: white
Melting point: 825 °C1,098.15 K <br />1,517 °F <br />1,976.67 °R <br />
Decomposition point: 1000 °C1,273.15 K <br />1,832 °F <br />2,291.67 °R <br /> (calcite)
Refractive index: 1.59 (calcite)
1.51 (aragonite)
Optical properties: birefringence
Magnetic properties: diamagnetic
χ=-3.82 · 10-5cm³/mol
Hardness: very fragile
Toxicity: non-toxic


Inorganic compound, salt of alkaline earth metal calcium and inorganic carbonic acid. Doesn't form water hydrates.


Occurs in nature as calcite, aragonite, vaterite, chalk, marble, travertine, ikaite, glendonite and pearl minerals.

Where to buy

In hardware store (as "marble crumb", "marble flour"), office supply store (as "chalk" - mixed calcium carbonate and sulfate), fertilizers store and grocery store (eggshell).


Reaction between calcium chloride or nitrate and baking soda, sodium carbonate or potassium carbonate

Chemical equation:

Ca(NO3)2 + 2NaHCO3 = CaCO3↓ + 2NaNO3 + H2O + CO2
Ca(NO3)2 + Na2CO3 = CaCO3↓ + 2NaNO3
Ca(NO3)2 + K2CO3 = CaCO3↓ + 2KNO3
CaCl2 + 2NaHCO3 = CaCO3↓ + 2NaCl + H2O + CO2
CaCl2 + Na2CO3 = CaCO3↓ + 2NaCl
CaCl2 + K2CO3 = CaCO3↓ + 2KCl

For preparation of 100.00g of calcium carbonate а 235.94g of calcium nitrate tetrahydrate or 218.89g of calcium chloride hexahydrate and 167.87g of soda or 105.90g of sodium carbonate or 138.09g of potassium carbonate is required.
Take two plastic or glass containers connected with a tube at center or bottom. Connection should be hermetic.

Place silicic acid gel in the tube.
Then add solution of calcium nitrate or chloride to the first container and soda, sodium or potassium carbonate to the another one. Pour solutions simultaneously otherwise gel will pour out from tube. Cover containers with a cap (you can leave them non-hermetic) and leave for long time at room temperature.
During long time reagents will slowly diffuse deeper into the thickness the gel, reacts with small parts if meeting. A slow crystal growing of the slight soluble reaction product will begin.


Grows with simultaneous synthesis. Evaporation or cooling method could not be used because of the extremely low solubility.

Storage conditions

Store in its original form or under several layers of varnish at average humidity and room temperature. Do not store in matchboxes or cotton wool and do not heat.


Temperatureгр/100,00 гр water
20°C293.15 K <br />68 °F <br />527.67 °R <br />0.001437
25°C298.15 K <br />77 °F <br />536.67 °R <br />0.001522
Insoluble in ethanol.