What is Calcium carbonate: Definition and 18 Discussions

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which is a type of sedimentary rock consisting mainly of calcite) and is the main component of eggshells, snail shells, seashells and pearls. Calcium carbonate is the active ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale. It has medical use as a calcium supplement or as an antacid, but excessive consumption can be hazardous and cause hypercalcemia and digestive issues; as well it was noted that "many calcium supplement formulations contain [the chemical element] Lead and thereby may pose an easily avoidable public health concern," especially in those supplements which were not derived from natural oyster shells.

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  1. C

    Equilibrium pressure of calcium carbonate

    Homework Statement Calcium carbonate primarily occurs as two crystalline forms, calcite and aragonite. The value of∆!° for the transition CaCO3(calcite) ⇌ CaCO3(aragonite) is +1.04 kJ·mol-1 at 25°C. At that temperature the density for calcite is 2.710 g·cm-3, and that of aragonite is 2.930...
  2. emma69

    How does lime flocculate clay soil

    Hello guys, I have another question for you that I am stressing myself over, I would value your insights. Thanks in advance. When you add lime (Calcium carbonate) to clay soil it flocculates it and improves the structure, how does this happen ?
  3. M

    Unwanted Calcium Carbonate in Refractory Cement

    I have noticed that most castable refractories effervesce if mixed with acid. In context, this is orthophosphoric acid added to promote the formation of a calcium-aluminium phosphate bonding phase. In one case, I estimated that 40% of the calcium aluminate cement had become carbonated by...
  4. E

    Will Ca(HCO3)2(aq) + 2NH3(aq) react?

    Hi, I'm wondering if an aqueous solution of Calcium Bicarbonate and Ammonia would react to form Ammonium Bicarbonate and Calcium Hydroxide. Additionally, would Calcium Carbonate react with Ammonia in solution to form Ammonium Carbonate? EJ
  5. Y

    Calcium Carbonate & Dicalcium Phosphate - CO2 Problem

    Hello everyone, I would really appreciate your help on figuring out the issue of undesirable CO2 production in this situation. Homework Statement In a mixture of CaCO3 + CaHPO4; I am observing undesirable CO2 production under conditions of 20-25°C (room temp) and an undesirable excess of...
  6. W

    Thermal decomposition of calcium carbonate - problem

    Hello, here goes the problem: The mass of calcium carbonate upon thermal decomposition decreased by 1/5. (a) How many molecules of CaCO3 per 100 molecules were decomposed to CaO and CO2. (b) The content of CaO in the final sample express in molar fraction. My solution: I set the starting...
  7. M

    Thermal decomposition of calcium carbonate ?

    In general, we heat CaCO3 to temperature of approximately 825°C it decomposes into calcium oxide and liberates carbon dioxide gas: CaCO3 →825°C→ CaO + CO2 Is it possible to heat the calcium carbonate at temperatures below 825 degrees Celsius, so the decomposition into calcium oxide.
  8. D

    Slow precipitation of calcium carbonate.

    Hello Everyone, I am working with CaCO3. I want to have the precipitated CaCO3 in the laboratory. The easy way is to mix Na2CO3 and CaCl2. It gives CaCO3 and NaCl but this reaction takes place in a flash. As the reaction rate is high the produced CaCO3 forms powder like substance (the syze of...
  9. V

    Calcium Carbonate -> Calcium Oxide, but only getting Hydroxide. Ideas?

    I was trying to calcine some CaCO3 (Calcium Carbonate), but ended up with Calcium Hydroxide. To test if I had Calcium Carbonate I added it to some vinegar, no gas was produced. I then mixed in a small amount of the powder with a large amount of water and passed CO2 through it, and it became a...
  10. P

    Calcium carbonate sample -> calcite or aragonite?

    Calcium carbonate sample --> calcite or aragonite? Is there a definite way to determine whether a calcium carbonate sample is calcite or aragonite? The weak bond of aragonite should produce an active reaction with a weak acid such as diluted acetic (vinegar), whereas calcite will require a...
  11. S

    How Does Pressure Influence the Stability of Calcium Carbonate Phases?

    Homework Statement Calcium carbonate (\mathrm{CaCO_3}) has two common crystal forms: Calcite and Aragonite. In room temperature and atmospheric pressure, the Calcite has Gibbs energy -1128.8 kJ/mol, volume 36.93 cm^3/mol and entropy 92.9 J/K/mol, and the Aragonite has Gibbs energy -1127.8...
  12. M

    Reactions of calcium carbonate

    Hi What is the reaction of calcium carbonate and water. I thought it was insoluble but I was looking up some notes from a chemistry practical i did and it says CaCO3(s) + H2O (l) → Ca(OH)2(s) + CO2(g) Can someone please explain this reaction for me as I can't find it on the internet...
  13. S

    General formula for Calcium carbonate

    How do u derive a general formula (without undue approximations) to calculate the solubility of CaCO3(s) in a aqueous solution at any pH? Thanks
  14. A

    Reaction of Calcium Carbonate in Water with Hydrochloric Acid

    I was told to design an experiment and run it during my chemistry lab period, and I came up with the following idea: Soil usually is limed with calcium carbonate containing products (agricultural lime) in order to raise the pH of the solution. Thus, I first isolated the amount of calcium from...
  15. P

    Stoichiometry: yield of reaction between hydrochloric acid and calcium carbonate

    Thank you in advance for the correction of the resolution. Homework Statement By reacting 225 g of hydrochloric acid with 300 g of calcium carbonate with 80% of purity, 34 L (litres) of gas were obtained, measured at 37oC and a pression of 0.82 atm. What is the yield of this reaction and what...
  16. M

    Caffeine and Dichloromethane Reaction: Formation of C8H9O2N4+

    Caffeine & Dichloromethane What are the products of caffeine & dichloromethane? I think caffeine is acting as the acid, and dichloromethane as the base. So, the caffeine is releasing H+ into the solution. So would the equation be: C8H10O2N4 + CH2Cl2 --> C8H9O2N4+ + (I have no...
  17. H

    Equilibrium Constant for Calcium Carbonate Reaction at 500 C

    Calcium Carbonate is heated in a closed vessel, and an equilibrium is reached. CaCO3 (s) <=> CaO(s) + CO2 (g) At 500 C the equilibrium pressure of carbon dioxide is 1.2*10^-3 atm and at 1000 C it is 3.87 atm. what is the equilibrium constant for this reaction at 500 C? :confused:
  18. J

    Comparing Calcium Carbonate in Shells: An Experiment

    what experiment should i conduct to compare the amounts of calcium carbonate in 2 different shells... i believe this might be of use: acid + carbonate = salt + water + carbon dioxide my email is janice_ling88@yahoo.com.sg