Aqueous Ionic Equilibria

These flashcards cover the key vocabulary related to aqueous ionic equilibria, focusing on buffer solutions, titration, and related concepts.

Buffer Solution

A solution that contains significant amounts of a weak acid and its conjugate base or a weak base and its conjugate acid.

Weak Acid

An acid that only partially dissociates in solution.

Conjugate Base

The species that remains after an acid donates a hydrogen ion.

pH Stability

Buffers resist changes in pH when small amounts of strong acids or bases are added.

H2CO3

Carbonic acid, a weak acid found in blood.

Sodium Acetate

A salt (NaC2H3O2) used as a source of the conjugate base in acidic buffer solutions.

Buffer Capacity

The amount of acid or base that can be added to a buffer solution without significantly changing its pH.

Henderson–Hasselbalch Equation

A formula used to calculate the pH of a buffer solution: pH = pKa + log([base]/[acid]).

pKa

The negative logarithm of the acid dissociation constant (Ka), indicating the strength of the acid.

Acidic Buffer

A buffer composed of a weak acid and its conjugate base.

Basic Buffer

A buffer composed of a weak base and its conjugate acid.

Equivalence Point

The point in titration at which the moles of titrant equal the moles of the substance being titrated.

Conjugate Acid

The species formed when a base gains a hydrogen ion.

Stoichiometry Calculation

Calculating the amounts of reactants and products involved in a chemical reaction.

Neutralization Reaction

A chemical reaction where an acid and a base react to form water and a salt.

HC2H3O2

Acetic acid, a weak acid commonly used in buffer solutions.

NaOH

Sodium hydroxide, a strong base used to adjust pH.

HCl

Hydrochloric acid, a strong acid used to adjust pH.

Significant Change in pH

A notable variation in pH that occurs when the buffering capacity of a solution is exceeded.

Sample Calculation for pH

Determining the pH of a buffer solution using initial concentration of acid and conjugate base.

Aqueous Solutions

Solutions in which water is the solvent.

Buffering Effectiveness

The ability of a buffer to maintain pH when acids or bases are added.

NH3

Ammonia, a common weak base used in basic buffer solutions.

NH4Cl

Ammonium chloride, a salt that provides the conjugate acid in basic buffer solutions.

Titration Curve

A graph of pH versus the volume of titrant added.

Indicator

A chemical that changes color at a specific pH range to indicate the endpoint of a titration.

Endpoint

The point in titration at which the indicator shows that the reaction is complete.

pH Calculation After Acid Addition

Determining new pH after adding an acid to a buffer involves stoichiometry and equilibrium calculations.

Weak Base

A base that only partially dissociates in solution.

Ka

The acid dissociation constant, a measure of the strength of an acid.

Kb

The base dissociation constant, a measure of the strength of a base.

Polyprotic Acid

An acid that can donate more than one proton per molecule.

Titration of Weak Acid

Process of adding a strong base to a weak acid to determine pH changes.

Buffering Range

The pH range in which a buffer is effective.

Buffer Concentration

The total concentration of acid and conjugate base in a buffer solution.

Dilute Buffer

A buffer with low concentrations of acid and base components.

Concentration Effect

How the concentrations of acid and base affect the buffering capacity.

pOH Calculation

Calculating the pH indirectly by determining the pOH of the solution.