The equilibrium concentration of Sr
2+ is constant. You couldn't it count by taking square root of K
sp because CO
32- hydrolyzes and the concentartion of it changes during solution. Thanks to that process (the hydrolysis) the solubity of SrCO
3 is bigger than it result from square root of K
sp (2,98x10
-5 < 2,2x10
-4). During the solution when CO
32- hydrolyzes, the concentration of it decreases, so the K
sp isn't exeeded, so bigger amount of salt can be soluted.
"The carbonate ion which dissolves forms HCO3- in a 1:1 molar ratio or remains unreacted." What does this statement mean??
It means only that CO
32- can dissolves to HCO
3- or not. And if one molecules of CO
32- hydrolizes, one molecule of HCO
3- comes into being (so the molar ratio 1:1). That deduction results from the reaction's equation.
I hope I clarify it to you. If not, ask.