Introduction to Equilibrium - AP Chemistry
Card 1 of 30
What is the general form of the equilibrium constant expression?
What is the general form of the equilibrium constant expression?
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$K = \frac{\text{[products]}}{\text{[reactants]}}$. Products in numerator, reactants in denominator, each raised to their coefficients.
$K = \frac{\text{[products]}}{\text{[reactants]}}$. Products in numerator, reactants in denominator, each raised to their coefficients.
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What is the role of coefficients in equilibrium expressions?
What is the role of coefficients in equilibrium expressions?
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They become exponents for concentration terms in $K$ expressions. Stoichiometric coefficients become powers in the equilibrium constant expression.
They become exponents for concentration terms in $K$ expressions. Stoichiometric coefficients become powers in the equilibrium constant expression.
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What is the significance of a dynamic equilibrium?
What is the significance of a dynamic equilibrium?
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Reactants and products form at the same rate. Concentrations remain constant while reactions continue in both directions.
Reactants and products form at the same rate. Concentrations remain constant while reactions continue in both directions.
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What happens when $Q = K$ during a reaction process?
What happens when $Q = K$ during a reaction process?
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The system is at equilibrium. No driving force exists for net reaction in either direction.
The system is at equilibrium. No driving force exists for net reaction in either direction.
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What does a low $K$ value suggest about the reaction?
What does a low $K$ value suggest about the reaction?
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Significant formation of reactants at equilibrium. Small $K$ indicates equilibrium strongly favors reactant formation.
Significant formation of reactants at equilibrium. Small $K$ indicates equilibrium strongly favors reactant formation.
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Compare $Q$ and $K$ to predict the direction of a reaction shift.
Compare $Q$ and $K$ to predict the direction of a reaction shift.
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If $Q < K$, shifts right; if $Q > K$, shifts left. Compares current state to equilibrium to predict reaction direction.
If $Q < K$, shifts right; if $Q > K$, shifts left. Compares current state to equilibrium to predict reaction direction.
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Identify the effect of adding a product on the position of equilibrium.
Identify the effect of adding a product on the position of equilibrium.
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Shifts towards the reactant side. System shifts to consume the added product by forming more reactants.
Shifts towards the reactant side. System shifts to consume the added product by forming more reactants.
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What is the definition of Le Chatelier's Principle?
What is the definition of Le Chatelier's Principle?
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Systems at equilibrium react to disturbances by shifting to counteract the change. Equilibrium shifts to oppose external changes and restore balance.
Systems at equilibrium react to disturbances by shifting to counteract the change. Equilibrium shifts to oppose external changes and restore balance.
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What does a high $K$ value suggest about the reaction?
What does a high $K$ value suggest about the reaction?
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Significant formation of products at equilibrium. Large $K$ indicates equilibrium strongly favors product formation.
Significant formation of products at equilibrium. Large $K$ indicates equilibrium strongly favors product formation.
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Identify the effect of adding a reactant on the position of equilibrium.
Identify the effect of adding a reactant on the position of equilibrium.
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Shifts towards the product side. System shifts to consume the added reactant by forming more products.
Shifts towards the product side. System shifts to consume the added reactant by forming more products.
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What is the effect of temperature change on $K$?
What is the effect of temperature change on $K$?
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$K$ changes; depends on reaction's endothermic or exothermic nature. Temperature is the only factor that changes the equilibrium constant value.
$K$ changes; depends on reaction's endothermic or exothermic nature. Temperature is the only factor that changes the equilibrium constant value.
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What is the effect of changing concentration on the equilibrium constant?
What is the effect of changing concentration on the equilibrium constant?
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No effect; $K$ is constant at a given temperature. Only temperature affects $K$; concentration changes shift position only.
No effect; $K$ is constant at a given temperature. Only temperature affects $K$; concentration changes shift position only.
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Identify the effect of increasing temperature on an endothermic reaction at equilibrium.
Identify the effect of increasing temperature on an endothermic reaction at equilibrium.
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Shifts towards the product side. Higher temperature favors the endothermic direction (forward reaction).
Shifts towards the product side. Higher temperature favors the endothermic direction (forward reaction).
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What is the relationship between $K_c$ and $K_p$?
What is the relationship between $K_c$ and $K_p$?
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$K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is moles of gas change. Converts between concentration and pressure equilibrium constants.
$K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is moles of gas change. Converts between concentration and pressure equilibrium constants.
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What is the definition of chemical equilibrium?
What is the definition of chemical equilibrium?
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The state where the rates of forward and reverse reactions are equal. Forward and reverse reaction rates balance, maintaining constant concentrations.
The state where the rates of forward and reverse reactions are equal. Forward and reverse reaction rates balance, maintaining constant concentrations.
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Identify the effect of decreasing temperature on an exothermic reaction at equilibrium.
Identify the effect of decreasing temperature on an exothermic reaction at equilibrium.
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Shifts towards the product side. Lower temperature favors the exothermic direction (forward reaction).
Shifts towards the product side. Lower temperature favors the exothermic direction (forward reaction).
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Define homogeneous equilibrium.
Define homogeneous equilibrium.
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Equilibrium where all reactants and products are in the same phase. All species exist in one phase (all gas, liquid, or aqueous).
Equilibrium where all reactants and products are in the same phase. All species exist in one phase (all gas, liquid, or aqueous).
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Define heterogeneous equilibrium.
Define heterogeneous equilibrium.
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Equilibrium with reactants and products in different phases. Species exist in multiple phases (solid, liquid, gas, aqueous combinations).
Equilibrium with reactants and products in different phases. Species exist in multiple phases (solid, liquid, gas, aqueous combinations).
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State the expression for the equilibrium constant $K_p$ for the reaction $aA + bB \rightleftharpoons cC + dD$.
State the expression for the equilibrium constant $K_p$ for the reaction $aA + bB \rightleftharpoons cC + dD$.
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$K_p = \frac{P_C^c P_D^d}{P_A^a P_B^b}$. Uses partial pressures instead of concentrations in the equilibrium expression.
$K_p = \frac{P_C^c P_D^d}{P_A^a P_B^b}$. Uses partial pressures instead of concentrations in the equilibrium expression.
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What is the unit for the equilibrium constant $K_c$?
What is the unit for the equilibrium constant $K_c$?
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Unitless; derived from concentration terms. Concentration units cancel out in the ratio of products to reactants.
Unitless; derived from concentration terms. Concentration units cancel out in the ratio of products to reactants.
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What does a $K_c$ value less than 1 indicate?
What does a $K_c$ value less than 1 indicate?
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Reactants are favored at equilibrium. Smaller $K$ means equilibrium lies toward the reactant side.
Reactants are favored at equilibrium. Smaller $K$ means equilibrium lies toward the reactant side.
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Identify the effect of decreasing pressure on the position of equilibrium.
Identify the effect of decreasing pressure on the position of equilibrium.
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Shifts towards the side with more moles of gas. Lower pressure favors the side with more gas molecules to increase volume.
Shifts towards the side with more moles of gas. Lower pressure favors the side with more gas molecules to increase volume.
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How does the addition of an inert gas affect equilibrium?
How does the addition of an inert gas affect equilibrium?
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No effect on the position of equilibrium. Inert gases don't participate in the reaction or affect concentrations.
No effect on the position of equilibrium. Inert gases don't participate in the reaction or affect concentrations.
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Identify the effect of increasing pressure on the position of equilibrium in a gaseous reaction.
Identify the effect of increasing pressure on the position of equilibrium in a gaseous reaction.
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Shifts towards the side with fewer moles of gas. Pressure increase favors the side with less gas molecules to reduce volume.
Shifts towards the side with fewer moles of gas. Pressure increase favors the side with less gas molecules to reduce volume.
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What does a $K_c$ value greater than 1 indicate?
What does a $K_c$ value greater than 1 indicate?
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Products are favored at equilibrium. Larger $K$ means equilibrium lies toward the product side.
Products are favored at equilibrium. Larger $K$ means equilibrium lies toward the product side.
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What is the relationship between $K_c$ and $K_p$?
What is the relationship between $K_c$ and $K_p$?
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$K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is moles of gas change. Converts between concentration and pressure equilibrium constants.
$K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is moles of gas change. Converts between concentration and pressure equilibrium constants.
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What happens to $K$ when a reaction is multiplied by a factor?
What happens to $K$ when a reaction is multiplied by a factor?
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$K$ is raised to the power of that factor. Multiplying equation by $n$ raises the equilibrium constant to power $n$.
$K$ is raised to the power of that factor. Multiplying equation by $n$ raises the equilibrium constant to power $n$.
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What is the significance of $K$ being temperature-dependent?
What is the significance of $K$ being temperature-dependent?
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Equilibrium position changes with temperature. Different temperatures give different $K$ values for the same reaction.
Equilibrium position changes with temperature. Different temperatures give different $K$ values for the same reaction.
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What is the unit for the equilibrium constant $K_p$?
What is the unit for the equilibrium constant $K_p$?
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Unitless; derived from partial pressure terms. Pressure units cancel out in the ratio of products to reactants.
Unitless; derived from partial pressure terms. Pressure units cancel out in the ratio of products to reactants.
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How is the reaction direction affected by $Q$?
How is the reaction direction affected by $Q$?
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Determines if the reaction shifts left or right to reach equilibrium. Comparison of $Q$ and $K$ predicts which direction favors equilibrium.
Determines if the reaction shifts left or right to reach equilibrium. Comparison of $Q$ and $K$ predicts which direction favors equilibrium.
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