When the rate of precipitation becomes equal to the rate of dissolving,a condition of dynamic multiphase equilibrium is established. BaSO(s) 溶 沉 -Ba2(aq)+O (aq K(BaSO)=[c(Ba)/cellc(SO )/c] or simply:Ke(BaSO)={c(Ba))(c(SO ) KP一solubility product constant(溶度积常数) For general precipitation reactions: A,B(s)=nAT(aq)+mB"-(ag) Ke(A B)=(A)"(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 + - K = c c c c sp 溶解 BaSO (s) Ba (aq) SO (aq) 2 4 2 4 + - + 沉淀