AP Chemistry Flashcards: Representations Of Equilibrium

What this deck covers

This deck focuses on Representations Of 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 relationship between $K_p$ and $K_c$ for a gas-phase reaction?

Answer: $K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is the change in moles of gas. Accounts for the pressure difference when converting between concentration and pressure equilibrium constants.

Flashcard 2: Identify the condition when $Q = K_c$ in a chemical reaction.

Answer: The system is at equilibrium. When the reaction quotient equals the equilibrium constant, rates are balanced.

Flashcard 3: Identify the principle that explains the effect of concentration changes on equilibrium.

Answer: Le Chatelier's Principle. States that systems respond to stress by shifting to counteract the disturbance.

Flashcard 4: What is the unit of $K_c$ for the reaction $N_2 + 3H_2 \rightleftharpoons 2NH_3$?

Answer: M^{-2}. Units are $\frac{M^2}{M \cdot M^3} = M^{-2}$ based on the concentration terms.

Flashcard 5: What happens to equilibrium when an inert gas is added at constant volume?

Answer: No change in equilibrium position. At constant volume, adding inert gas doesn't change partial pressures of reactants.

Flashcard 6: What is the effect of decreasing volume on the equilibrium of a reaction with gases?

Answer: Equilibrium shifts toward the side with fewer moles of gas. System reduces stress by shifting to the side that occupies less volume.

Flashcard 7: State the effect of removing heat from an endothermic reaction.

Answer: Shifts equilibrium to the left (toward reactants). Heat is treated as a reactant in endothermic reactions, so removing heat shifts left.

Flashcard 8: What does a $K_{eq} = 1$ indicate about a reaction?

Answer: Neither reactants nor products are favored. Equal concentrations of reactants and products at equilibrium when $K_{eq} = 1$.

Flashcard 9: What is the effect of adding more $H_2O$ to a gaseous equilibrium system?

Answer: No effect if $H_2O$ is not a reactant or product in gaseous form. Liquid water doesn't affect gas-phase equilibria unless it participates as a gas.

Flashcard 10: What is the effect of adding more $N_2$ to the equilibrium $N_2 + 3H_2 \rightleftharpoons 2NH_3$?

Answer: Equilibrium shifts right, producing more $NH_3$. Adding reactants increases their concentration, driving the reaction forward.

Flashcard 11: What is the general effect of pressure increase on a gaseous equilibrium?

Answer: Shifts towards the side with fewer moles of gas. System responds to pressure increase by reducing the total number of gas molecules.

Flashcard 12: State the effect of temperature increase on an exothermic reaction's equilibrium position.

Answer: Shifts the equilibrium to the left (toward reactants). Heat is treated as a product in exothermic reactions, so adding heat shifts left.

Flashcard 13: What is $Q$ for the reaction $2A \rightleftharpoons B + C$ if $[A]=2$, $[B]=1$, $[C]=3$?

Answer: $Q = \frac{[B][C]}{[A]^2} = \frac{1 \times 3}{2^2} = 0.75$. Using $Q = \frac{[B][C]}{[A]^2}$ with the given concentrations.

Flashcard 14: Identify the factor that does not affect the value of $K_c$ for a reaction.

Answer: Pressure changes do not affect $K_c$.. Only temperature changes affect $K_c$; pressure and concentration changes don't.

Flashcard 15: What is the $K_c$ expression for $H_2 + I_2 \rightleftharpoons 2HI$?

Answer: $K_c = \frac{[HI]^2}{[H_2][I_2]}$. Products raised to stoichiometric coefficients over reactants raised to their coefficients.

Flashcard 16: How does the addition of a common ion affect the solubility of a salt?

Answer: Solubility decreases due to the common ion effect. Increased concentration of a common ion shifts equilibrium toward the undissolved solid.

Flashcard 17: How do you determine the direction of the shift if $Q > K_c$?

Answer: The reaction shifts left towards reactants. When $Q > K_c$, there are too many products relative to equilibrium.

Flashcard 18: What is the expression for $K_{sp}$ of $CaF_2$?

Answer: $K_{sp} = [Ca^{2+}][F^-]^2$. Products of ion concentrations raised to their stoichiometric coefficients for the dissolution.

Flashcard 19: What is the Le Chatelier's response to the removal of a product from the equilibrium mixture?

Answer: Equilibrium shifts right to produce more product. Removing products decreases $Q$, making the forward reaction more favorable.

Flashcard 20: What is the relationship between $K_p$ and $K_c$ for a gas-phase reaction?

Answer: $K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is the change in moles of gas. Accounts for the pressure difference when converting between concentration and pressure equilibrium constants.

Flashcard 21: What is the significance of $K_{eq} > 1$ for a chemical reaction?

Answer: Products are favored at equilibrium. Large equilibrium constants mean the forward reaction is thermodynamically favorable.

Flashcard 22: What does a very small $K_c$ value indicate about a reaction?

Answer: The reaction favors reactants at equilibrium. Small $K_c$ values mean the equilibrium position lies far to the left.

Flashcard 23: What is the effect of decreasing volume on the equilibrium of a reaction with gases?

Answer: Equilibrium shifts toward the side with fewer moles of gas. System reduces stress by shifting to the side that occupies less volume.

Flashcard 24: What is the effect on equilibrium when a solid reactant is added?

Answer: No effect on the equilibrium position. Solid concentrations don't appear in equilibrium expressions and don't affect position.

Flashcard 25: How does $K_{eq}$ relate to the spontaneity of a reaction?

Answer: $K_{eq} > 1$ indicates a spontaneous reaction. Large equilibrium constants indicate thermodynamically favorable forward reactions.

Flashcard 26: What is the result of tripling the volume of a gaseous equilibrium system?

Answer: Shifts towards the side with more moles of gas. Increasing volume decreases pressure, favoring the side with more gas molecules.

Flashcard 27: Identify the effect of pressure decrease on equilibrium with equal moles of gas on both sides.

Answer: No change in equilibrium position. When $\Delta n = 0$, pressure changes don't affect equilibrium position.

Flashcard 28: What is the expression for $K_{sp}$ of $CaF_2$?

Answer: $K_{sp} = [Ca^{2+}][F^-]^2$. Products of ion concentrations raised to their stoichiometric coefficients for the dissolution.

Flashcard 29: What does a $K_{eq} = 1$ indicate about a reaction?

Answer: Neither reactants nor products are favored. Equal concentrations of reactants and products at equilibrium when $K_{eq} = 1$.

Flashcard 30: How does the addition of a non-reactive gas affect the equilibrium position?

Answer: No effect on the equilibrium position. Inert gases don't participate in the reaction and don't change partial pressures.

Flashcard 31: Describe how a catalyst affects the position of equilibrium.

Answer: A catalyst does not affect the position of equilibrium. Catalysts only speed up the rate of reaching equilibrium but don't change the final position.

Flashcard 32: In which direction will equilibrium shift when $K_c < Q$?

Answer: Shifts left, towards reactants. When $Q > K_c$, there are excess products, so the reaction proceeds backward.

Flashcard 33: What is the relationship between $K_p$ and $K_c$ for a gas-phase reaction?

Answer: $K_p = K_c(RT)^{\Delta n}$, where $\Delta n$ is the change in moles of gas. Accounts for the pressure difference when converting between concentration and pressure equilibrium constants.

Flashcard 34: How does the addition of a non-reactive gas affect the equilibrium position?

Answer: No effect on the equilibrium position. Inert gases don't participate in the reaction and don't change partial pressures.

Flashcard 35: How does the addition of a common ion affect the solubility of a salt?

Answer: Solubility decreases due to the common ion effect. Increased concentration of a common ion shifts equilibrium toward the undissolved solid.

Flashcard 36: What happens to $K_c$ when the temperature is changed?

Answer: $K_c$ changes with temperature. Temperature is the only factor that changes the equilibrium constant value.

Flashcard 37: What is the result of doubling the concentration of reactants at equilibrium?

Answer: Equilibrium shifts right, producing more products. Increasing reactant concentration makes the forward reaction more favorable.

Flashcard 38: Identify the factor that does not affect the value of $K_c$ for a reaction.

Answer: Pressure changes do not affect $K_c$.. Only temperature changes affect $K_c$; pressure and concentration changes don't.

Flashcard 39: What is the relationship between $K_{sp}$ and solubility?

Answer: Higher $K_{sp}$ indicates greater solubility. Larger $K_{sp}$ values correspond to more soluble compounds at equilibrium.

Flashcard 40: What is the Le Chatelier's response to the removal of a product from the equilibrium mixture?

Answer: Equilibrium shifts right to produce more product. Removing products decreases $Q$, making the forward reaction more favorable.

Flashcard 41: What happens to $K_c$ when the temperature is changed?

Answer: $K_c$ changes with temperature. Temperature is the only factor that changes the equilibrium constant value.

Flashcard 42: What is the Le Chatelier's response to the removal of a product from the equilibrium mixture?

Answer: Equilibrium shifts right to produce more product. Removing products decreases $Q$, making the forward reaction more favorable.

Flashcard 43: What is the effect of decreasing volume on the equilibrium of a reaction with gases?

Answer: Equilibrium shifts toward the side with fewer moles of gas. System reduces stress by shifting to the side that occupies less volume.

Flashcard 44: What is the expression for $K_{sp}$ of $CaF_2$?

Answer: $K_{sp} = [Ca^{2+}][F^-]^2$. Products of ion concentrations raised to their stoichiometric coefficients for the dissolution.

Flashcard 45: Identify the condition when $Q = K_c$ in a chemical reaction.

Answer: The system is at equilibrium. When the reaction quotient equals the equilibrium constant, rates are balanced.

Flashcard 46: How does the addition of a common ion affect the solubility of a salt?

Answer: Solubility decreases due to the common ion effect. Increased concentration of a common ion shifts equilibrium toward the undissolved solid.

Flashcard 47: What happens to $K_c$ when the temperature is changed?

Answer: $K_c$ changes with temperature. Temperature is the only factor that changes the equilibrium constant value.

Flashcard 48: State the effect of removing heat from an endothermic reaction.

Answer: Shifts equilibrium to the left (toward reactants). Heat is treated as a reactant in endothermic reactions, so removing heat shifts left.

Flashcard 49: What is the result of doubling the concentration of reactants at equilibrium?

Answer: Equilibrium shifts right, producing more products. Increasing reactant concentration makes the forward reaction more favorable.

Flashcard 50: What is the unit of $K_c$ for the reaction $N_2 + 3H_2 \rightleftharpoons 2NH_3$?

Answer: M^{-2}. Units are $\frac{M^2}{M \cdot M^3} = M^{-2}$ based on the concentration terms.

Flashcard 51: What is the relationship between $K_{sp}$ and solubility?

Answer: Higher $K_{sp}$ indicates greater solubility. Larger $K_{sp}$ values correspond to more soluble compounds at equilibrium.

Flashcard 52: Identify the condition when $Q = K_c$ in a chemical reaction.

Answer: The system is at equilibrium. When the reaction quotient equals the equilibrium constant, rates are balanced.

Flashcard 53: Identify the factor that does not affect the value of $K_c$ for a reaction.

Answer: Pressure changes do not affect $K_c$.. Only temperature changes affect $K_c$; pressure and concentration changes don't.

Flashcard 54: What is the effect of increasing the temperature on $K_c$ for an exothermic reaction?

Answer: $K_c$ decreases. For exothermic reactions, higher temperature makes products less stable, decreasing $K_c$.

Flashcard 55: What does a very small $K_c$ value indicate about a reaction?

Answer: The reaction favors reactants at equilibrium. Small $K_c$ values mean the equilibrium position lies far to the left.

Flashcard 56: What is the effect of diluting a solution at equilibrium?

Answer: Shifts towards the side with more moles of dissolved species. Dilution favors the side that produces more particles to maintain equilibrium.

Flashcard 57: What is the effect of adding more $N_2$ to the equilibrium $N_2 + 3H_2 \rightleftharpoons 2NH_3$?

Answer: Equilibrium shifts right, producing more $NH_3$. Adding reactants increases their concentration, driving the reaction forward.

Flashcard 58: What is the unit of $K_c$ for the reaction $N_2 + 3H_2 \rightleftharpoons 2NH_3$?

Answer: M^{-2}. Units are $\frac{M^2}{M \cdot M^3} = M^{-2}$ based on the concentration terms.

Flashcard 59: What is the effect of diluting a solution at equilibrium?

Answer: Shifts towards the side with more moles of dissolved species. Dilution favors the side that produces more particles to maintain equilibrium.

Flashcard 60: What is the effect of diluting a solution at equilibrium?

Answer: Shifts towards the side with more moles of dissolved species. Dilution favors the side that produces more particles to maintain equilibrium.

Flashcard 61: State the effect of removing heat from an endothermic reaction.

Answer: Shifts equilibrium to the left (toward reactants). Heat is treated as a reactant in endothermic reactions, so removing heat shifts left.

Flashcard 62: How does the addition of a non-reactive gas affect the equilibrium position?

Answer: No effect on the equilibrium position. Inert gases don't participate in the reaction and don't change partial pressures.

Flashcard 63: What is the result of doubling the concentration of reactants at equilibrium?

Answer: Equilibrium shifts right, producing more products. Increasing reactant concentration makes the forward reaction more favorable.

Flashcard 64: What does a very small $K_c$ value indicate about a reaction?

Answer: The reaction favors reactants at equilibrium. Small $K_c$ values mean the equilibrium position lies far to the left.