Glossary
Acidic Conjugate Acids
Cations or molecules that are the conjugate acids of weak bases and can react with OH⁻ ions in solution. This reaction reduces their concentration, increasing the solubility of their parent compounds in basic conditions.
Example:
The ammonium ion (NH₄⁺) in NH₄Cl is an acidic conjugate acid because it can react with OH⁻ to form NH₃ and H₂O, making NH₄Cl more soluble in base.
Basic Conjugate Bases
Anions that are the conjugate bases of weak acids and can react with H⁺ ions in solution. This reaction reduces the anion concentration, increasing the solubility of their parent compounds in acidic conditions.
Example:
The fluoride ion (F⁻) from CaF₂ is a basic conjugate base because it can react with H⁺ to form HF, making CaF₂ more soluble in acid.
Common Ion Effect
The decrease in the solubility of a sparingly soluble salt when a soluble salt containing a common ion is added to the solution. This shifts the dissolution equilibrium to the left.
Example:
Adding sodium chloride to a saturated solution of silver chloride will decrease the common ion effect of silver chloride because of the added chloride ions.
Equilibrium
A state in which the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in reactant and product concentrations.
Example:
In a saturated solution of salt, there's a dynamic equilibrium where solid salt dissolves at the same rate that dissolved ions precipitate.
Le Chatelier's Principle
States that if a change of condition (like concentration, temperature, or pressure) is applied to a system in equilibrium, the system will shift in a direction that counteracts the change.
Example:
If you add more product to a reaction at Le Chatelier's Principle, the equilibrium will shift towards the reactants to consume the added product.
Neutral Ions
Ions that are the conjugate acids of strong bases or conjugate bases of strong acids. They do not react significantly with H⁺ or OH⁻ ions in solution, so their parent compounds' solubility is not affected by pH changes.
Example:
Sodium ions (Na⁺) and chloride ions (Cl⁻) are neutral ions because they come from strong bases (NaOH) and strong acids (HCl), respectively, and do not affect pH.
Solubility
The maximum amount of a substance that can dissolve in a given amount of solvent at a specific temperature to form a saturated solution. It is an equilibrium process.
Example:
The solubility of sugar in hot tea is much higher than in cold tea, allowing more sugar to dissolve.
pH
A measure of the hydrogen ion concentration in a solution, indicating its acidity or alkalinity. It is calculated as the negative logarithm of the H⁺ concentration.
Example:
A solution with a pH of 2 is highly acidic, while a solution with a pH of 12 is strongly basic.