AP Chemistry Flashcards: Introduction To Equilibrium

What this deck covers

This deck focuses on Introduction To Equilibrium, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is the general form of the equilibrium constant expression?

Answer: $K = \frac{\text{[products]}}{\text{[reactants]}}$. Products in numerator, reactants in denominator, each raised to their coefficients.

Flashcard 2: What is the role of coefficients in equilibrium expressions?

Answer: They become exponents for concentration terms in $K$ expressions. Stoichiometric coefficients become powers in the equilibrium constant expression.

Flashcard 3: What is the significance of a dynamic equilibrium?

Answer: Reactants and products form at the same rate. Concentrations remain constant while reactions continue in both directions.

Flashcard 4: What happens when $Q = K$ during a reaction process?

Answer: The system is at equilibrium. No driving force exists for net reaction in either direction.

Flashcard 5: What does a low $K$ value suggest about the reaction?

Answer: Significant formation of reactants at equilibrium. Small $K$ indicates equilibrium strongly favors reactant formation.

Flashcard 6: Compare $Q$ and $K$ to predict the direction of a reaction shift.

Answer: If $Q < K$, shifts right; if $Q > K$, shifts left. Compares current state to equilibrium to predict reaction direction.

Flashcard 7: Identify the effect of adding a product on the position of equilibrium.

Answer: Shifts towards the reactant side. System shifts to consume the added product by forming more reactants.

Flashcard 8: What is the definition of Le Chatelier's Principle?

Answer: Systems at equilibrium react to disturbances by shifting to counteract the change. Equilibrium shifts to oppose external changes and restore balance.

Flashcard 9: What does a high $K$ value suggest about the reaction?

Answer: Significant formation of products at equilibrium. Large $K$ indicates equilibrium strongly favors product formation.

Flashcard 10: Identify the effect of adding a reactant on the position of equilibrium.

Answer: Shifts towards the product side. System shifts to consume the added reactant by forming more products.

Flashcard 11: What is the effect of temperature change on $K$?

Answer: $K$ changes; depends on reaction's endothermic or exothermic nature. Temperature is the only factor that changes the equilibrium constant value.

Flashcard 12: What is the effect of changing concentration on the equilibrium constant?

Answer: No effect; $K$ is constant at a given temperature. Only temperature affects $K$; concentration changes shift position only.

Flashcard 13: Identify the effect of increasing temperature on an endothermic reaction at equilibrium.

Answer: Shifts towards the product side. Higher temperature favors the endothermic direction (forward reaction).

Flashcard 14: What is the relationship between $K_c$ and $K_p$?

Answer: $K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is moles of gas change. Converts between concentration and pressure equilibrium constants.

Flashcard 15: What is the definition of chemical equilibrium?

Answer: The state where the rates of forward and reverse reactions are equal. Forward and reverse reaction rates balance, maintaining constant concentrations.

Flashcard 16: Identify the effect of decreasing temperature on an exothermic reaction at equilibrium.

Answer: Shifts towards the product side. Lower temperature favors the exothermic direction (forward reaction).

Flashcard 17: Define homogeneous equilibrium.

Answer: Equilibrium where all reactants and products are in the same phase. All species exist in one phase (all gas, liquid, or aqueous).

Flashcard 18: Define heterogeneous equilibrium.

Answer: Equilibrium with reactants and products in different phases. Species exist in multiple phases (solid, liquid, gas, aqueous combinations).

Flashcard 19: State the expression for the equilibrium constant $K_p$ for the reaction $aA + bB \rightleftharpoons cC + dD$.

Answer: $K_p = \frac{P_C^c P_D^d}{P_A^a P_B^b}$. Uses partial pressures instead of concentrations in the equilibrium expression.

Flashcard 20: What is the unit for the equilibrium constant $K_c$?

Answer: Unitless; derived from concentration terms. Concentration units cancel out in the ratio of products to reactants.

Flashcard 21: What does a $K_c$ value less than 1 indicate?

Answer: Reactants are favored at equilibrium. Smaller $K$ means equilibrium lies toward the reactant side.

Flashcard 22: Identify the effect of decreasing pressure on the position of equilibrium.

Answer: Shifts towards the side with more moles of gas. Lower pressure favors the side with more gas molecules to increase volume.

Flashcard 23: How does the addition of an inert gas affect equilibrium?

Answer: No effect on the position of equilibrium. Inert gases don't participate in the reaction or affect concentrations.

Flashcard 24: Identify the effect of increasing pressure on the position of equilibrium in a gaseous reaction.

Answer: Shifts towards the side with fewer moles of gas. Pressure increase favors the side with less gas molecules to reduce volume.

Flashcard 25: What does a $K_c$ value greater than 1 indicate?

Answer: Products are favored at equilibrium. Larger $K$ means equilibrium lies toward the product side.

Flashcard 26: What is the relationship between $K_c$ and $K_p$?

Answer: $K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is moles of gas change. Converts between concentration and pressure equilibrium constants.

Flashcard 27: What happens to $K$ when a reaction is multiplied by a factor?

Answer: $K$ is raised to the power of that factor. Multiplying equation by $n$ raises the equilibrium constant to power $n$.

Flashcard 28: What is the significance of $K$ being temperature-dependent?

Answer: Equilibrium position changes with temperature. Different temperatures give different $K$ values for the same reaction.

Flashcard 29: What is the unit for the equilibrium constant $K_p$?

Answer: Unitless; derived from partial pressure terms. Pressure units cancel out in the ratio of products to reactants.

Flashcard 30: How is the reaction direction affected by $Q$?

Answer: Determines if the reaction shifts left or right to reach equilibrium. Comparison of $Q$ and $K$ predicts which direction favors equilibrium.