solubility + complex ion equilibria

soluble salts

large amount of solid salt dissolves in water (greater than 10g/L)

slightly soluble salts

a small amount of the soil salt dissolves in water (between 0.1 - 1 g/L)

insoluble salts

only a small of solid salt dissolved in water ( less than 0.1 g/L)

solubility units

g/L

molar solubility units

mol/L

common ion effect in solubility equilibria

When the concentration of a common ion is increased in a solution at equilibrium, the system shifts to the left, favoring the formation of more solid. This reduces the solubility of the salt by decreasing the amount of dissolved ions in solution.

when determining the solubility eq of OH salts

whichever [OH] of water auto ionization or from the insoluble salt is greater is used to calculate

insoluble BASES tend to dissolve in

ACIDIC solutions

insoluble ACIDS tend to dissolve in

BASIC solutions

insoluble salts containing BASIC anions

increase their solubility in more acidic solition

dynamic equlibrium

when dissolution and crystallization occur at the same rate

saturated solution

when the quantity of dissolved solute remains constant with time

solubility of the solute

the concentration of saturated solution

solubility cuvre

a solublility vs temp graph

selective/fractional precipitation

A method used to separate ions in a mixture based on differences in their solubility. By carefully adding a reagent (like a common ion), the least soluble compound precipitates first, while more soluble ions remain dissolved. This allows for step-by-step isolation of specific ions from a solution

Nitrates (NO₃⁻)

soluble

Alkali metal salts (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺)

soluble

Ammonium salts (NH₄⁺)

soluble

Chlorides, bromides, iodides (except with Ag⁺, Pb²⁺, Hg₂²⁺)

soluble

Sulfates (except BaSO₄, PbSO₄, Hg₂SO₄, CaSO₄)

soluble

Hydroxides (except Na⁺, K⁺, and slightly Ba²⁺, Sr²⁺, Ca²⁺)

INsoluble

Sulfides (S²⁻)

INsoluble

Carbonates (CO₃²⁻)

INsoluble

Chromates (CrO₄²⁻)

INsoluble

Phosphates (PO₄³⁻)

Insoluble

Exception: These are soluble if paired with

alkali metals or NH₄⁺

coordination complex

when a metal ion is surrounded by a group of anions or ligands

ligands

neutral molecules

by Le Chatelier’s Principle, the addition of a ligand

can increase the solubility of the metal cation product