Determine the molar solubility of mgco3 in pure water. ksp (mgco3) = 6.82 × 10-6.

-when Ksp is the solubility product constant for a solid substance when it

dissolved in the solution, and measure how a solute dissolves in the solution.

- and when the solubility is the maximum quantity of solute which can dissolve in a certain solution. 

so according to the reaction equation:

MgCO3 ↔  Mg2+   +   CO32-

when the Ksp expression = [Mg2+][CO32-]

and when Ksp MgCO3= 6.82 x 10^-6 

and we assume [Mg2+]=[CO32-] = X 

and we assume the solubility is X

by substitution:

6.82 x 10^-6 = X^2

∴ X = √(6.82 X 10^-6)

      = 0.0026 M

∴ the solubility is 0.0026 M

They carry out the exchange of gases as we breathe ( oxygen and carbon dioxide).