Based on the fact that calcium carbonate is an ionic compound, why is it insoluble in water????
Look up your solubility rules. I'm not really sure why, but I know my book states right off that Most sulfide, carbonate, and phosphate salts are only slightly soluble. Slightly meaning that such a tiny amoutn dissolves that it's not possible to detect with the naked eye.
The lattice energy of CaCO3 is too high for the solvation energy with water molecules to break it up.
To understand why calcium carbonate (CaCO3) is insoluble in water, we need to consider the properties of ionic compounds and the solubility rules.
Ionic compounds are a combination of positively charged ions (cations) and negatively charged ions (anions) held together by strong electrostatic forces of attraction. In the case of calcium carbonate, it consists of a calcium ion (Ca2+) and carbonate ion (CO32-).
Solubility rules are guidelines based on experimental observations that determine whether an ionic compound is soluble or insoluble in water. According to the solubility rules, most sulfide, carbonate, and phosphate salts are only slightly soluble in water.
One reason for the insolubility of calcium carbonate in water is the high lattice energy. The lattice energy is the energy required to break apart the ionic solid into its constituent ions in the gas phase. In the case of calcium carbonate, it takes a significant amount of energy to separate the calcium ion from the carbonate ion, due to the strong electrostatic forces of attraction between them.
On the other hand, when an ionic compound dissolves in water, the solvent molecules surround the individual ions, breaking the crystal lattice structure and allowing the ions to move freely in the solution. This process is called solvation.
In the case of calcium carbonate, the solvation energy provided by water molecules is not sufficient to overcome the high lattice energy. As a result, only a small amount of calcium carbonate molecules dissolve in water, making it insoluble. The tiny amount that dissolves is so small that it cannot be detected with the naked eye.
So, to summarize, calcium carbonate is insoluble in water due to its high lattice energy, which cannot be overcome by the solvation energy provided by water molecules. By referring to the solubility rules, we can understand that most carbonate salts are only slightly soluble in water.