Write the equilibrium chemical equations for (i) the solubility equilibrium of calcium carbonate, and (ii) the base dissociation equilibrium of carbonate ion. Then discuss, in terms of Le Chatelier's principle, how changing pH influences the solubility of calcium carbonate.
First, let us state the Le Chatelier principle which deals with changes in an equilibrium:
The statement is as follows:
If any equilibrium is disturbed, that is, change in conditions such as P,T, concentration, partial pressure, etc.., the system will counterbalance such change in order to favour the system's equilbirium.
now...
CaCO3(s) <--> Ca2+ + CO3-2
CO3-2 + H+ <--> HCO3-
therefore, adding H+, will shift from CaCO3(s) to Ca+2 + CO3-2
since CO3-2 is decreasin, the system must counterbalance that
as pH increases, CaCO3 forms, as pH decreases, CaCO3 increase solubility
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