General formula for Calcium carbonate

[starlight5]

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

 

[Borek]

Start with all equations describing the solution - like dissociation equilibria, Kso, water ion product. Add to that charge balace and mass balances for carbonates and calcium. Solve for concentration of calcium.

That's the most general approach possible.

See pH calculation lectures, and especially lecture on pH of polyprotic acids. Equations 9.11, 9.12 and 9.13 can give you some hints.

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[quicknote]

for your question. I am happy to provide a response to your inquiry about the general formula for Calcium carbonate and how to derive a general formula to calculate its solubility in an aqueous solution at any pH.

The general formula for Calcium carbonate is CaCO3, which represents the chemical compound composed of one calcium atom, one carbon atom, and three oxygen atoms. This compound is commonly found in nature as a mineral, such as limestone, and is also an important component in many industrial processes.

To derive a general formula for calculating the solubility of CaCO3 in an aqueous solution at any pH, we need to understand the underlying chemical reactions that take place between CaCO3 and water. When CaCO3 is added to water, it undergoes a dissociation reaction, forming calcium ions (Ca2+) and carbonate ions (CO32-):

CaCO3(s) → Ca2+(aq) + CO32-(aq)

The solubility of CaCO3 in water depends on the equilibrium between the dissolved ions and the solid compound. This equilibrium is affected by the pH of the solution, as the concentration of hydrogen ions (H+) can influence the formation of carbonate ions. In acidic solutions, the H+ ions combine with the carbonate ions to form bicarbonate ions (HCO3-):

H+(aq) + CO32-(aq) → HCO3-(aq)

This reaction decreases the concentration of carbonate ions and shifts the equilibrium towards the solid form of CaCO3. On the other hand, in basic solutions, the H+ ions are consumed by the hydroxide ions (OH-) present, leading to an increase in the concentration of carbonate ions and promoting the dissolution of CaCO3.

Based on these chemical reactions, we can derive a general formula for calculating the solubility of CaCO3 in an aqueous solution at any pH:

[Ca2+] × [CO32-] = Ksp × [HCO3-]n

Where [Ca2+] and [CO32-] represent the concentration of dissolved calcium and carbonate ions, respectively, Ksp is the solubility product constant for CaCO3, and [HCO3-]n is the concentration of bicarbonate ions raised to the power of its stoichiometric coefficient in the dissociation reaction.

This formula takes into account the effects of pH on the solubility of CaCO3 by considering the concentration of bicarbonate ions