Fundamental Equilibrium Concepts

This set of flashcards covers key concepts and vocabulary in fundamental equilibrium concepts, chemical equilibrium, acids and bases, pH, and buffer solutions.

Chemical Equilibrium

A state in a chemical reaction where the rates of the forward and reverse reactions are equal.

Rate Constant (k)

A constant that relates the rate of a reaction to the concentration of reactants.

Equilibrium Constant (K)

A value that expresses the ratio of concentrations of products to reactants at equilibrium.

Reaction Quotient (Q)

The ratio of the concentrations of products to reactants at any point in time.

Dynamic Nature of Equilibrium

Equilibrium is dynamic as reactions continue to occur, but there is no net change in concentration.

Homogeneous Reactions

Reactions where all reactants and products are in the same phase.

Heterogeneous Reactions

Reactions involving species in different phases.

Kp

Equilibrium constant expressed in terms of partial pressures.

Kc

Equilibrium constant expressed in terms of concentrations.

Le Chatelier’s Principle

If a system at equilibrium is stressed, the system shifts to counteract the stress.

Conjugate Acid-Base Pair

Acids and bases that differ by the presence of a proton.

pH scale

A scale used to measure the acidity or basicity of a solution.

pOH scale

A scale used to measure the hydroxide ion concentration in a solution.

Ka

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

Kb

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

Amphiprotic Substances

Substances that can act as either an acid or a base.

Hydronium ion ( ext{H}_3 ext{O}^+)

The ion formed when an acid donates a proton to water.

Hydroxide ion ( ext{OH}^-)

The ion formed when a base dissociates in water.

Percent Ionization

The ratio of the concentration of the ionized form of an acid or base to the initial concentration, expressed as a percentage.

Buffer Solution

A solution that resists changes in pH when small amounts of acid or base are added.

Buffer Capacity

The amount of acid or base a buffer solution can neutralize before a significant change in pH occurs.

Solubility Product Constant (Ksp)

An equilibrium constant for the dissolution of an ionic compound.

Common-Ion Effect

The decrease in the solubility of a salt when another source of one of its ions is added.

ICE Table

A table used to calculate the concentrations of reactants and products at equilibrium.

Acid Ionization Constant (K_a)

The equilibrium constant for the ionization of an acid.

Base Ionization Constant (K_b)

The equilibrium constant for the ionization of a base.

Weak Acid

An acid that does not completely ionize in solution.

Weak Base

A base that does not completely ionize in solution.

Strong Acid

An acid that completely ionizes in solution.

Strong Base

A base that completely ionizes in solution.

Binary Acids

Acids composed of hydrogen and one other element.

Oxoacids

Acids that contain oxygen and are bonded to a hydrogen atom and another element.

Equilibrium Concentrations

The concentrations of reactants and products at equilibrium.

Factors Affecting Equilibrium

Changes in concentration, temperature, and pressure that can shift the position of equilibrium.

Ion-Product Constant for Water (K_w)

The equilibrium constant for the autoionization of water, equal to $1.0 imes 10^{-14}$ at $25^ ext{°C}$.

Amphoteric Species

Species that can act as either an acid or a base depending on the circumstances.

Acidic Solution

A solution with a pH less than 7.

Basic Solution

A solution with a pH greater than 7.

Neutral Solution

A solution with a pH equal to 7.

Hydrolysis of Salts

The reaction of a salt with water to produce an acidic or basic solution.

Reaction Direction

The direction in which the equilibrium will shift in response to a change.

Equilibrium Shift

The change in the position of equilibrium in response to a change in condition.

Pressure and Volume Changes

Changes that can affect the equilibrium position when gaseous reactants or products are involved.

Catalyst in Equilibrium

A substance that speeds up the rate of both the forward and reverse reactions without affecting the position of equilibrium.

Concentration Changes

Alterations in the amount of reactants or products that can shift the equilibrium.

Temperature Changes

Adjustments in temperature that can influence the equilibrium position of a reaction.