Question #399f7

1 Answer
May 27, 2017

Answer:

Add more acetic acid (HOAc)

Explanation:

Adding acid into an aqueous solution functions to deliver hydronium ions #(H_3O^+)# into the solution. If ions of Calcium and Carbonate are present, Hydrogen ions #(H^+)# from the #H_3O^+# will coordinate (bond) with the carbonate ion #(CO_3^(2-))# forming the weak acid 'Hydrogen Carbonate' #((H-CO_3)^-)#.

Hydrogen Carbonate is no longer part of the Calcium Carbonate Equilibrium which is now deficient in carbonate ions on the product side of the equilibrium.

#CaCO_3# #rightleftharpoons Ca^(2+) + CO_3^(2-)# => #CaCO_3 => Ca^(2+) + (_)#

Additional unionized Calcium Carbonate then ionizes in order to replace the #CO_3^(2-)# that combined with #H^+# from the acetic acid.

This is typically described by saying "the equilibrium
#CaCO_3# #rightleftharpoons Ca^(2+) + CO_3^(2-)# shifts to the right increasing solubility of the #CaCO_3#".