These simple calculations give rough information (ignoring real solution effects) about what happens in pure water. But suppose the water contained sodium chloride?
NaCl has such a large Ksp value (» 29) that for all practical purposes it is simply "soluble". So a solution of sodium chloride contains free sodium and chloride ions and essentially "no" NaCl. If we now add silver chloride to such a solution, what might we expect?
One way to think about this situation is to imagine the reverse happening. We take the solution of silver chloride mentioned at the beginning and add sodium chloride to it. To simplify matters and avoid dilution considerations, let's add solid NaCl.
As the salt is added it dissolves and more free chloride ions enter the solution.