Cadmium (Cd) is reported to be much more toxic as the free metal (Cd^2+) than when complexed with ligands. The total soluble Cd concentration (Cgamma, Cd = [Cd^2+] 4- the sum of all soluble Cd complexes) in a water is measured to be 10^-4M. In order to ensure that the toxicity of Cd is small, it is desirable to have Cd^2+ be less than 10^-7 M. An environmental engineer suggests adding 0.5 M NaCl to complex the Cd^2+. Ignore activity corrections and the formation of any solids. Consider only the complexes of chloride with cadmium-there are 4 (log beta1 = 2.0, log beta2 = 2.6, log beta3 = 2.4, and log beta4 = 1.7).
A. Will this help keep [Cd^2+] below 10^-7 M?
B. What is [Cd^2+]?