Question

If calcium iodate, Ca(IO3)2, is dissolved in a calcium nitrate solution, instead of DI water, does the equilibrium concentration of iodate ions: 
a. increase, b. decrease, or remain the same?

Answer 1

The equilibrium reactions of both calclium nitrate and calcium iodate are given below

Ca(NO3)2 (aq) <---> Ca2+ (aq) + 2NO3-(aq)

Ca(IO3)2 (aq) <----> Ca2+ (aq) + 2IO3- (aq)

thus when Ca(IO3)2 is added to Ca(NO3)2 solution the concentration of Ca2+ (aq) increases thus the equilibrium is shifted towards left had side of reaction ( common ion effect) i.e the excess Ca2+ will react with IO32- to form Ca(IO3)2 ,

thus concentration of IO3-   i.e iodate ions decreases