When the rate of precipitation becomes equal to the rate of dissolving,a condition of dynamic multiphase equilibrium is established. BaSO(s)- 溶解 Ba2*(aq)+SO(aq) 沉淀 K(BaSO)=[c(Ba2)/ce][c(SO)/ce] or simply:K(BaSO)={c(Ba)c(SO) K吊一solubility product constant(溶度积常数) For general precipitation reactions: A B(s)-nAm*(aq)+mB"(aq) K9(ABm)={d(Am)}”{d(B")}"When the rate of precipitation becomes equal to the rate of dissolving, a condition of dynamic multiphase equilibrium is established. For general precipitation reactions： Ksp — solubility product constant (溶度积常数） A B (s) nA (aq) mB (aq) m n n m + - + m n n m (AnBm) { (A )} { (B )} + - Ksp = c c (BaSO ) { (Ba )}{ (SO )} 2 4 2 4 + - or simply： Ksp = c c (BaSO ) [ (Ba )/ ][ (SO )/ ] 2 4 2 4 + - Ksp = c c c c 溶解 BaSO (s) Ba (aq) SO (aq) 2 4 2 4 + - + 沉淀