General Chemistry • Solubility and Complex Ion Equilibria
Compare Qsp with Ksp after mixing ionic solutions, or estimate how complete precipitation is when one ion stays effectively constant. The calculator supports generic AmBn stoichiometries, shows step-by-step calculations, and draws interactive graphs only when results are ready.
Recognized keys: mode, model, Ksp, precision, Aconc, Avol, Bconc, Bvol, Bdrops, Bdropvol, Bstock, A0, Bconst.
Qsp is the ion product calculated from the current ion concentrations in the mixture, using the same exponents as the Ksp expression. Ksp is the equilibrium constant at a given temperature, so comparing Qsp to Ksp predicts whether precipitation will occur.
A precipitate forms when Qsp is greater than Ksp for the possible solid A_mB_n. If Qsp is less than Ksp, the mixture is unsaturated and no precipitate forms; if Qsp equals Ksp, the system is at the threshold.
The calculator uses the diluted concentrations based on total volume after mixing. For example, [A]0 is found from the moles of A added divided by the total mixed volume, and the same approach is used for B (including the drop-based option).
Completeness describes how much of ion A remains in solution at equilibrium when ion B is held at a constant concentration. A small remaining fraction means the precipitation is nearly complete, while a larger remaining fraction indicates significant A stays dissolved.
Even after precipitation starts, equilibrium requires that ion concentrations satisfy the Ksp expression, so some ions must remain in solution. A fixed or high common-ion concentration can greatly reduce solubility, but equilibrium still limits removal to a nonzero remaining concentration.