Final answer:
The solubility of CaCO3 in seawater increases with increasing acidity. This can be attributed to the formation of carbonic acid from dissolved CO2, which leads to a reaction that dissolves calcium carbonate, increasing the levels of calcium and bicarbonate ions.
Step-by-step explanation:
The trend in the solubility of CaCO3 as seawater becomes more acidic is that solubility increases. This increase in solubility happens because CO2 levels rise in the atmosphere and dissolve in the ocean, forming carbonic acid which reacts with calcium carbonate:
- H2O + CO2 = H2CO3
- CaCO3 + H2CO3 = Ca2+ + 2HCO3-
This results in higher concentrations of calcium and bicarbonate ions, illustrating an increase in the solubility of CaCO3 in an acidic environment caused by rising CO2 levels. The equilibrium constant for this reaction is much greater than the Ksp for calcium carbonate, which also indicates a marked increase in solubility in acidic conditions.