Question 253015

Question: The reactions for the dissolution of limestone (CaCO3(s)) and for the dissociation of bicarbonate ion (HCO3–) to carbonateion (CO32–) are as follows:

These reactions have reached equilibrium in a solution at pH 9.33 that contains10−2 mol/L CaCO3(s) and10−3.3 mol/L Ca2+.

a. What is the HCO3– concentration in the solution, assuming that activity coefficientsforall species are1.0? b. Would you expect the Ca2+ concentration to increase, decrease, or not change if the system changed in the following ways? For this part of the problem, do not assume that activity coefficients are 1.0. In each case, explain your reasoning briefly (1-2 sentences). For this part of the question, consider only the effecton thefirstreaction shown above. I. The concentrationof CaCO3(s) is doubled. II. The ionic strength of the solutionincreases, e.g., by addition of NaCl. III. The pH is lowered slightly, without significantly altering the ionic strength.