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⚖️AP Chemistry Unit 7 Vocabulary

92 essential vocabulary terms and definitions for Unit 7 – Equilibrium

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⚖️Unit 7 – Equilibrium
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⚖️Unit 7 – Equilibrium

7.10 Reaction Quotient and Le Châtelier’s Principle

TermDefinition
concentrationThe amount of solute dissolved in a given volume of solution, typically expressed in molarity or other units of amount per volume.
disturbanceA change or stress applied to a system at equilibrium that causes Q to differ from K and shifts the system out of equilibrium.
equilibriumThe state in which the forward and reverse reaction rates are equal, resulting in constant concentrations or partial pressures of reactants and products.
equilibrium constantA numerical value that expresses the ratio of products to reactants at equilibrium, indicating the extent to which a reaction proceeds.
partial pressureThe pressure exerted by a single gas in a mixture of gases, used in equilibrium expressions for gas-phase reactions.
reaction quotientA value calculated using the same expression as the equilibrium constant but using current (non-equilibrium) concentrations or partial pressures.

7.1 Introduction to Equilibrium

TermDefinition
absorptionThe process by which a gas is taken up by a solid or liquid.
concentrationThe amount of solute dissolved in a given volume of solution, typically expressed in molarity or other units of amount per volume.
condensationThe process by which a gas converts to a liquid.
desorptionThe process by which an absorbed gas is released from a solid or liquid.
dissolutionThe process by which a solute dissolves in a solvent to form a solution, involving the breaking of bonds or interactions in the solute and formation of new interactions with the solvent.
dynamic equilibriumA state of equilibrium in which forward and reverse reactions continue to occur at equal rates, maintaining constant macroscopic properties.
electron transferThe movement of one or more electrons from one chemical species to another in a redox reaction.
equilibriumThe state in which the forward and reverse reaction rates are equal, resulting in constant concentrations or partial pressures of reactants and products.
evaporationThe process by which a liquid converts to a gas.
partial pressureThe pressure exerted by a single gas in a mixture of gases, used in equilibrium expressions for gas-phase reactions.
precipitationThe process by which a dissolved solute forms a solid and separates from a solution.
proton transferThe movement of a proton (H⁺) from one species to another in an acid-base reaction.
reversible processA chemical or physical process that can occur in both forward and reverse directions, such as evaporation-condensation or dissolution-precipitation.

7.11 Introduction to Solubility Equilibria

TermDefinition
balanced chemical equationA chemical equation where the number of atoms of each element is equal on both the reactant and product sides.
dissolutionThe process by which a solute dissolves in a solvent to form a solution, involving the breaking of bonds or interactions in the solute and formation of new interactions with the solvent.
equilibrium systemA system in which the forward and reverse reactions occur at equal rates, resulting in constant concentrations of reactants and products.
KspThe solubility product constant; the equilibrium constant for the dissolution of a sparingly soluble salt into its ions.
molar solubilityThe solubility of a substance expressed as the number of moles of solute that dissolve per liter of solution in a saturated solution.
saltAn ionic compound formed from the reaction of an acid and a base.
saturated solutionA solution that contains the maximum amount of dissolved solute at a given temperature, in equilibrium with undissolved solute.
solubilityThe maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature, typically expressed in moles per liter (molarity) or grams per 100 mL of solvent.
solubility rulesGuidelines that predict whether an ionic compound is soluble or insoluble in water based on the identity of the cation and anion.
soluble saltsIonic compounds that dissolve readily in water, typically corresponding to Ksp values greater than 1.
stoichiometryThe quantitative relationship between reactants and products in a balanced chemical equation that determines the rates of change of their concentrations.

7.12 Common Ion Effect

TermDefinition
common ionAn ion that is already present in a solution and is also produced by the dissolution of a salt added to that solution.
common-ion effectThe phenomenon in which the solubility of a salt is reduced when dissolved in a solution that already contains one of the ions present in the salt.
dissolutionThe process by which a solute dissolves in a solvent to form a solution, involving the breaking of bonds or interactions in the solute and formation of new interactions with the solvent.
KspThe solubility product constant; the equilibrium constant for the dissolution of a sparingly soluble salt into its ions.
Le Châtelier's principleA principle stating that when a system at equilibrium is disturbed, the system shifts to counteract the disturbance and re-establish equilibrium.
saltAn ionic compound formed from the reaction of an acid and a base.
solubilityThe maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature, typically expressed in moles per liter (molarity) or grams per 100 mL of solvent.

7.2 Direction of Reversible Reactions

TermDefinition
equilibrium stateThe condition reached when the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in the amounts of reactants and products.
forward reactionThe reaction pathway in which reactants are converted to products.
net conversionThe overall change in the amounts of reactants or products as a result of the forward and reverse reactions occurring simultaneously.
reaction rateThe speed at which reactants are converted to products per unit of time in a chemical reaction.
reverse reactionThe reaction that proceeds from products back to reactants, opposite to the direction written in the balanced chemical equation.
reversible reactionA chemical reaction that can proceed in both the forward and reverse directions, with reactants forming products and products reforming reactants.

7.3 Reaction Quotient and Equilibrium Constant

TermDefinition
equilibrium constantA numerical value that expresses the ratio of products to reactants at equilibrium, indicating the extent to which a reaction proceeds.
equilibrium expressionA mathematical equation that relates the concentrations or partial pressures of reactants and products at equilibrium, expressed as Kc or Kp.
KcThe equilibrium constant expressed in terms of molar concentrations of reactants and products at equilibrium.
KpThe equilibrium constant expressed in terms of partial pressures of gaseous reactants and products at equilibrium.
law of mass actionThe principle that the equilibrium expression for a reversible reaction is the ratio of the concentrations (or partial pressures) of products to reactants, each raised to the power of their stoichiometric coefficients.
partial pressureThe pressure exerted by a single gas in a mixture of gases, used in equilibrium expressions for gas-phase reactions.
reaction quotientA value calculated using the same expression as the equilibrium constant but using current (non-equilibrium) concentrations or partial pressures.
reversible reactionA chemical reaction that can proceed in both the forward and reverse directions, with reactants forming products and products reforming reactants.

7.4 Calculating the Equilibrium Constant

TermDefinition
concentrations at equilibriumThe molar amounts of reactants and products per unit volume when a reversible reaction reaches equilibrium and no net change occurs.
equilibrium constant expressionA mathematical expression that relates the concentrations or partial pressures of products and reactants at equilibrium, with each raised to the power of its stoichiometric coefficient.
KcThe equilibrium constant expressed in terms of molar concentrations of reactants and products at equilibrium.
KpThe equilibrium constant expressed in terms of partial pressures of gaseous reactants and products at equilibrium.
partial pressuresThe individual pressure exerted by each gas in a mixture of gases at equilibrium.

7.5 Magnitude of the Equilibrium Constant

TermDefinition
chemical speciesA distinct chemical entity such as an atom, molecule, or ion that participates in a chemical reaction.
equilibrium concentrationsThe concentrations of reactants and products when a reversible reaction reaches equilibrium and no further net change occurs.
equilibrium constantA numerical value that expresses the ratio of products to reactants at equilibrium, indicating the extent to which a reaction proceeds.
proceeds to completionA reaction that converts essentially all reactants to products, occurring when the equilibrium constant is very large.

7.6 Properties of the Equilibrium Constant

TermDefinition
equilibrium constantA numerical value that expresses the ratio of products to reactants at equilibrium, indicating the extent to which a reaction proceeds.
multistep processA reaction mechanism consisting of two or more elementary steps that combine to produce an overall reaction.
overall equilibrium expressionThe equilibrium constant expression for the net reaction obtained by adding multiple elementary steps together.
reaction quotientA value calculated using the same expression as the equilibrium constant but using current (non-equilibrium) concentrations or partial pressures.
stoichiometric coefficientsThe numerical coefficients in a balanced chemical equation that indicate the relative proportions of reactants and products.

7.7 Calculating Equilibrium Concentrations

TermDefinition
balanced reactionA chemical equation in which the number of atoms of each element is equal on both sides of the equation.
chemical speciesA distinct chemical entity such as an atom, molecule, or ion that participates in a chemical reaction.
concentrationThe amount of solute dissolved in a given volume of solution, typically expressed in molarity or other units of amount per volume.
dynamic equilibriumA state of equilibrium in which forward and reverse reactions continue to occur at equal rates, maintaining constant macroscopic properties.
equilibriumThe state in which the forward and reverse reaction rates are equal, resulting in constant concentrations or partial pressures of reactants and products.
equilibrium constantA numerical value that expresses the ratio of products to reactants at equilibrium, indicating the extent to which a reaction proceeds.
forward reactionThe reaction pathway in which reactants are converted to products.
initial conditionsThe starting concentrations or partial pressures of reactants and products before a reaction reaches equilibrium.
net consumptionThe overall decrease in the amount of a substance as a result of a chemical reaction.
partial pressuresThe individual pressure exerted by each gas in a mixture of gases at equilibrium.
reaction quotientA value calculated using the same expression as the equilibrium constant but using current (non-equilibrium) concentrations or partial pressures.
reverse reactionThe reaction that proceeds from products back to reactants, opposite to the direction written in the balanced chemical equation.

7.8 Representations of Equilibrium

TermDefinition
equilibriumThe state in which the forward and reverse reaction rates are equal, resulting in constant concentrations or partial pressures of reactants and products.
equilibrium constantA numerical value that expresses the ratio of products to reactants at equilibrium, indicating the extent to which a reaction proceeds.
particulate modelA representation of matter showing individual atoms, molecules, or ions and their interactions to describe chemical processes at the molecular level.
productSubstances formed as a result of a chemical reaction.
reactantSubstances that are consumed in a chemical reaction to form products.
reversible reactionA chemical reaction that can proceed in both the forward and reverse directions, with reactants forming products and products reforming reactants.

7.9 Introduction to Le Châtelier’s Principle

TermDefinition
chemical speciesA distinct chemical entity such as an atom, molecule, or ion that participates in a chemical reaction.
dilutionThe process of decreasing the concentration of a solute in a solution by adding solvent, which can shift equilibrium position.
equilibriumThe state in which the forward and reverse reaction rates are equal, resulting in constant concentrations or partial pressures of reactants and products.
external stressA change applied to a system at equilibrium, such as addition or removal of a chemical species, temperature change, pressure change, or dilution.
Le Châtelier's principleA principle stating that when a system at equilibrium is disturbed, the system shifts to counteract the disturbance and re-establish equilibrium.
pHA logarithmic scale used to express the concentration of hydronium ions in a solution, calculated as −log[H3O+].
pressureThe force exerted by gas molecules; changes in pressure of a gas-phase system can shift the equilibrium position.
temperatureA factor that influences reaction rate by affecting the kinetic energy and collision frequency of reactant molecules.
volumeThe space occupied by a system; changes in volume of a gas-phase system can shift equilibrium position.