Solubility of Salts K Foothill College（盐的溶解度K山麓上大学）.pdfVIP

Solubility of Salts - Ksp We now focus on another aqueous equilibrium system, slightly soluble salts. These salts have a Solubility Product Constant, Ksp . (We saw this in 1B with the sodium tetraborate solubility lab.) For example, K is defined for Cu(OH) (s) as follows: sp 2 2+ – 2+ – 2 –20 Cu(OH) (s) Cu (aq) + 2 OH (aq) K =[Cu ][OH ] = 4.8x10 at 25 °C 2 sp For a list of Ksp values at 25°C, refer to Appendix D-Table D.3. These slightly soluble salts dissolve until Ksp is satisfied. At this point, we say the solution is saturated, and no more salt will dissolve. In terms of Q we have the sp following possibilities: 1. Q K sp sp 2. Q = K sp sp 3. Qsp Ksp Other Aspects of Ionic Equilibria 1 Ksp Solubility Write the chemical equilibrium and the K equilibrium-constant expression for the solubility of Ca (PO ) . sp 3 4 2 Solubility and Ksp • The solubility of salts (saturated solution) are often expressed in one or more of the following units with the temperature also specified: mol/L (molar solubility) g/L , g/mL, g/100 mL or mg/L (Note that these are NOT densities.) ppm or ppb (parts per million or parts per billion) for very insoluble salts. • The above units for solubility are directly related to Ksp through equilibrium