H2 Chemistry 22 - Solubility product

solution that contains max amount of solute that can be dissolved in solvent @ given temp

max no. of moles of/mass of solute that can be dissolved in 1dm³ to form saturated solution @ fixed temp

1. temp

2. common ion effect

3. pH

4. complex ion formation

K_sp of sparingly soluble salt, is product of molar conc of ions in saturated solution, raised to appropriate powers

IP of solution is product of molar conc of constituent ions, raised to appropriate powers

IP<K_sp

all solid dissolves, solution is unsaturated, > solid can be dissolved

IP=K_sp

all solid dissolves but no more solid can dissolve, solution is saturated

IP>K_sp

excess solid that cannot stay dissolved precipitates out. reduces conc of ions in solution >

conc of ions decrease by forming precipitate, IP decreases until IP=K_sp, solution saturated

if sparingly soluble salt(<->) added to fully soluble salt(->) w/ common ion,

[common ion] increases, POE of eqm salt shifts left to decrease [common ion] >

presence of common ion decreases solubility of sparingly soluble salt

complex ion formation increases solubility of salt;

addition of reagent shifts POE of complex ion eqn right, forms stable complex ion >

[ion] decreases, IP of sparingly soluble salt decreases >

IP<K_sp, POE of sparingly soluble salt eqn shifts to dissolve solid completely

Ksp concept valid only for saturated solution of sparingly soluble salts, total concentrations of ions not > 0.0100moldm-3

for > concs, inter-ionic attractions occur & K_sp no longer constant