AP Chemistry Flashcards: Magnitude Of The Equilibrium Constant

What this deck covers

This deck focuses on Magnitude Of The Equilibrium Constant, 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 will happen to $K_c$ if the equation coefficients are doubled?

Answer: $K_c$ is squared. When coefficients are multiplied by $n$, $K$ is raised to the $n$th power.

Flashcard 2: For $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[SO_3]^2}{[SO_2]^2[O_2]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 3: What is the $K_c$ expression for $CO(g) + 2H_2(g) \rightleftharpoons CH_3OH(g)$?

Answer: $K_c = \frac{[CH_3OH]}{[CO][H_2]^2}$. Products over reactants, each raised to stoichiometric coefficients.

Flashcard 4: What happens to $K_c$ if the equation is reversed?

Answer: $K_c$ becomes $1/K_c$. Reversing the equation inverts the equilibrium constant.

Flashcard 5: Define the equilibrium constant $K$ in terms of partial pressures.

Answer: $K_p = \frac{(P_C)^c(P_D)^d}{(P_A)^a(P_B)^b}$ for gases. Equilibrium constant using partial pressures for gaseous species only.

Flashcard 6: How does changing volume affect $K_c$?

Answer: $K_c$ is unaffected. Volume changes affect concentrations but not $K_c$ value.

Flashcard 7: State how $K_c$ is affected by a change in concentration.

Answer: $K_c$ is unaffected. Equilibrium constant is independent of concentration changes.

Flashcard 8: If the equilibrium constant $K$ for a reaction is $0.01$, what does this suggest?

Answer: The reaction is reactant-favored. $K < 1$ means reactants predominate at equilibrium.

Flashcard 9: For the reaction $A \rightleftharpoons B$, if $K_c = 1$, what does this indicate?

Answer: The concentrations of products and reactants are equal. $K_c = 1$ means equal concentrations of A and B at equilibrium.

Flashcard 10: What does a small $K_c$ value indicate about the position of equilibrium?

Answer: The equilibrium favors reactants. Small $K$ means reactants are more abundant at equilibrium.

Flashcard 11: What is the effect on $K_c$ if the temperature increases for an endothermic reaction?

Answer: $K_c$ increases. Higher temperature favors endothermic direction (products).

Flashcard 12: What is true about the equilibrium constant when a reaction reaches equilibrium?

Answer: The rate of the forward and reverse reactions are equal. At equilibrium, the equilibrium constant value remains constant.

Flashcard 13: What is the effect on $K_c$ if the temperature decreases for an endothermic reaction?

Answer: $K_c$ decreases. Lower temperature shifts endothermic equilibrium toward reactants.

Flashcard 14: For the equilibrium $PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[PCl_3][Cl_2]}{[PCl_5]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 15: For the reaction $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[NH_3]^2}{[N_2][H_2]^3}$. Products over reactants, each raised to their stoichiometric coefficients.

Flashcard 16: What is the $K_c$ expression for $H_2(g) + I_2(g) \rightleftharpoons 2HI(g)$?

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

Flashcard 17: For $2NO(g) + O_2(g) \rightleftharpoons 2NO_2(g)$, provide the $K_c$ expression.

Answer: $K_c = \frac{[NO_2]^2}{[NO]^2[O_2]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 18: Predict how $K_c$ will shift if pressure is increased for $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$.

Answer: $K_c$ does not change. Equilibrium constant depends only on temperature, not pressure.

Flashcard 19: For the reaction $A \rightleftharpoons B$, if $K_c = 1$, what does this indicate?

Answer: The concentrations of products and reactants are equal. $K_c = 1$ means equal concentrations of A and B at equilibrium.

Flashcard 20: If $K_c = 1000$ for a reaction, is it product or reactant favored?

Answer: Product favored. $K > 1$ indicates products are favored at equilibrium.

Flashcard 21: What does a large $K_c$ value indicate about the position of equilibrium?

Answer: The equilibrium favors products. Large $K$ means products are more abundant at equilibrium.

Flashcard 22: What happens to $K_c$ if the equation is reversed?

Answer: $K_c$ becomes $1/K_c$. Reversing the equation inverts the equilibrium constant.

Flashcard 23: What is the expression for the equilibrium constant $K_c$ for the reaction $aA + bB \rightleftharpoons cC + dD$?

Answer: $K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}$. Products raised to coefficients over reactants raised to coefficients.

Flashcard 24: If $K_p = 5$ and $K_c = 5$ for a reaction, what is $\triangle n$?

Answer: $\triangle n = 0$. When $K_p = K_c$, the change in gas moles is zero.

Flashcard 25: Determine the $K_c$ expression for $2NO_2(g) \rightleftharpoons N_2O_4(g)$.

Answer: $K_c = \frac{[N_2O_4]}{[NO_2]^2}$. Products over reactants, with each raised to stoichiometric coefficients.

Flashcard 26: Predict how $K_c$ will shift if pressure is increased for $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$.

Answer: $K_c$ does not change. Equilibrium constant depends only on temperature, not pressure.

Flashcard 27: Determine the $K_c$ expression for $C(s) + CO_2(g) \rightleftharpoons 2CO(g)$.

Answer: $K_c = [CO]^2 / [CO_2]$. Solids are omitted from equilibrium expressions.

Flashcard 28: State how $K_c$ is affected by a change in concentration.

Answer: $K_c$ is unaffected. Equilibrium constant is independent of concentration changes.

Flashcard 29: For the reaction $2A(g) \rightleftharpoons B(g) + C(g)$, write the $K_p$ expression.

Answer: $K_p = \frac{P_B P_C}{P_A^2}$. Partial pressures of products over reactants, raised to coefficients.

Flashcard 30: For the reaction $2A(g) \rightleftharpoons B(g) + C(g)$, write the $K_p$ expression.

Answer: $K_p = \frac{P_B P_C}{P_A^2}$. Partial pressures of products over reactants, raised to coefficients.

Flashcard 31: State the relationship between $K_c$ and the rate constants $k_f$ and $k_r$ for a reaction.

Answer: $K_c = \frac{k_f}{k_r}$. Ratio of forward to reverse rate constants equals equilibrium constant.

Flashcard 32: What is the expression for $K_c$ for the decomposition of $H_2O(g)$ into $H_2(g)$ and $O_2(g)$?

Answer: $K_c = \frac{[H_2]^2[O_2]}{[H_2O]^2}$. Decomposition: $2H_2O(g) \rightleftharpoons 2H_2(g) + O_2(g)$.

Flashcard 33: Determine the $K_c$ expression for $CH_4(g) + 2O_2(g) \rightleftharpoons CO_2(g) + 2H_2O(g)$.

Answer: $K_c = \frac{[CO_2][H_2O]^2}{[CH_4][O_2]^2}$. Products over reactants, each raised to their stoichiometric coefficients.

Flashcard 34: What is the equilibrium constant $K_c$ for the reverse reaction if the forward reaction has $K_c = 10$?

Answer: $K_c = 0.1$. Reverse reaction constant equals $1/K_{forward}$.

Flashcard 35: What is the $K_c$ expression for the reaction $2H_2(g) + O_2(g) \rightleftharpoons 2H_2O(g)$?

Answer: $K_c = \frac{[H_2O]^2}{[H_2]^2[O_2]}$. Products over reactants, each raised to stoichiometric coefficients.

Flashcard 36: Determine the $K_c$ expression for $CH_4(g) + 2O_2(g) \rightleftharpoons CO_2(g) + 2H_2O(g)$.

Answer: $K_c = \frac{[CO_2][H_2O]^2}{[CH_4][O_2]^2}$. Products over reactants, each raised to their stoichiometric coefficients.

Flashcard 37: What does a small $K_c$ value indicate about the position of equilibrium?

Answer: The equilibrium favors reactants. Small $K$ means reactants are more abundant at equilibrium.

Flashcard 38: If the equilibrium constant $K$ for a reaction is $0.01$, what does this suggest?

Answer: The reaction is reactant-favored. $K < 1$ means reactants predominate at equilibrium.

Flashcard 39: Calculate $K_p$ from $K_c = 50$ for $H_2(g) + I_2(g) \rightleftharpoons 2HI(g)$ at 300 K.

Answer: $K_p = 50$. $\Delta n = 0$, so $K_p = K_c$.

Flashcard 40: What is the effect on $K_p$ if the temperature increases for an exothermic reaction?

Answer: $K_p$ decreases. Le Chatelier's principle: heat shifts equilibrium toward reactants.

Flashcard 41: What is the equilibrium expression for $K_c$ for the reaction $2SO_3(g) \rightleftharpoons 2SO_2(g) + O_2(g)$?

Answer: $K_c = \frac{[SO_2]^2[O_2]}{[SO_3]^2}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 42: What is the effect on $K_c$ if the temperature increases for an endothermic reaction?

Answer: $K_c$ increases. Higher temperature favors endothermic direction (products).

Flashcard 43: Determine the $K_c$ expression for $C(s) + CO_2(g) \rightleftharpoons 2CO(g)$.

Answer: $K_c = [CO]^2 / [CO_2]$. Solids are omitted from equilibrium expressions.

Flashcard 44: What is the expression for the equilibrium constant $K_c$ for the reaction $aA + bB \rightleftharpoons cC + dD$?

Answer: $K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}$. Products raised to coefficients over reactants raised to coefficients.

Flashcard 45: For the reaction $2A(g) \rightleftharpoons B(g) + C(g)$, write the $K_p$ expression.

Answer: $K_p = \frac{P_B P_C}{P_A^2}$. Partial pressures of products over reactants, raised to coefficients.

Flashcard 46: What is true about the equilibrium constant when a reaction reaches equilibrium?

Answer: The rate of the forward and reverse reactions are equal. At equilibrium, the equilibrium constant value remains constant.

Flashcard 47: For $N_2(g) + O_2(g) \rightleftharpoons 2NO(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[NO]^2}{[N_2][O_2]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 48: What is true about $K_c$ if a reaction is at equilibrium?

Answer: The value of $K_c$ is constant. At equilibrium, $K_c$ has a fixed value at constant temperature.

Flashcard 49: How does $K_c$ change if a catalyst is added to a reaction?

Answer: $K_c$ remains unchanged. Catalysts affect reaction rate but not equilibrium position.

Flashcard 50: Define the equilibrium constant $K$ in terms of partial pressures.

Answer: $K_p = \frac{(P_C)^c(P_D)^d}{(P_A)^a(P_B)^b}$ for gases. Equilibrium constant using partial pressures for gaseous species only.

Flashcard 51: State how $K_c$ is affected by a change in concentration.

Answer: $K_c$ is unaffected. Equilibrium constant is independent of concentration changes.

Flashcard 52: Identify the equilibrium constant expression $K_p$ for the reaction $aA(g) + bB(g) \rightleftharpoons cC(g) + dD(g)$.

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

Flashcard 53: Determine the $K_c$ expression for $C(s) + CO_2(g) \rightleftharpoons 2CO(g)$.

Answer: $K_c = [CO]^2 / [CO_2]$. Solids are omitted from equilibrium expressions.

Flashcard 54: How does changing volume affect $K_c$?

Answer: $K_c$ is unaffected. Volume changes affect concentrations but not $K_c$ value.

Flashcard 55: What is true about $K_c$ if a reaction is at equilibrium?

Answer: The value of $K_c$ is constant. At equilibrium, $K_c$ has a fixed value at constant temperature.

Flashcard 56: What is the effect on $K_p$ if the temperature increases for an exothermic reaction?

Answer: $K_p$ decreases. Le Chatelier's principle: heat shifts equilibrium toward reactants.

Flashcard 57: For the reaction $A \rightleftharpoons B$, if $K_c = 1$, what does this indicate?

Answer: The concentrations of products and reactants are equal. $K_c = 1$ means equal concentrations of A and B at equilibrium.

Flashcard 58: What is the equilibrium expression for $K_c$ for the reaction $2SO_3(g) \rightleftharpoons 2SO_2(g) + O_2(g)$?

Answer: $K_c = \frac{[SO_2]^2[O_2]}{[SO_3]^2}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 59: How does $K_c$ change if a catalyst is added to a reaction?

Answer: $K_c$ remains unchanged. Catalysts affect reaction rate but not equilibrium position.

Flashcard 60: Identify the equilibrium constant expression $K_p$ for the reaction $aA(g) + bB(g) \rightleftharpoons cC(g) + dD(g)$.

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

Flashcard 61: If $K_c = 1000$ for a reaction, is it product or reactant favored?

Answer: Product favored. $K > 1$ indicates products are favored at equilibrium.

Flashcard 62: What does a large $K_c$ value indicate about the position of equilibrium?

Answer: The equilibrium favors products. Large $K$ means products are more abundant at equilibrium.

Flashcard 63: Calculate $K_p$ from $K_c = 50$ for $H_2(g) + I_2(g) \rightleftharpoons 2HI(g)$ at 300 K.

Answer: $K_p = 50$. $\Delta n = 0$, so $K_p = K_c$.

Flashcard 64: For $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[SO_3]^2}{[SO_2]^2[O_2]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 65: What is the $K_c$ expression for $CO(g) + 2H_2(g) \rightleftharpoons CH_3OH(g)$?

Answer: $K_c = \frac{[CH_3OH]}{[CO][H_2]^2}$. Products over reactants, each raised to stoichiometric coefficients.

Flashcard 66: Determine the $K_c$ expression for $2NO_2(g) \rightleftharpoons N_2O_4(g)$.

Answer: $K_c = \frac{[N_2O_4]}{[NO_2]^2}$. Products over reactants, with each raised to stoichiometric coefficients.

Flashcard 67: What is the equilibrium constant $K_c$ for the reverse reaction if the forward reaction has $K_c = 10$?

Answer: $K_c = 0.1$. Reverse reaction constant equals $1/K_{forward}$.

Flashcard 68: What is the $K_c$ expression for $H_2(g) + I_2(g) \rightleftharpoons 2HI(g)$?

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

Flashcard 69: For $2NO(g) + O_2(g) \rightleftharpoons 2NO_2(g)$, provide the $K_c$ expression.

Answer: $K_c = \frac{[NO_2]^2}{[NO]^2[O_2]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 70: Determine the $K_c$ expression for $C(s) + CO_2(g) \rightleftharpoons 2CO(g)$.

Answer: $K_c = [CO]^2 / [CO_2]$. Solids are omitted from equilibrium expressions.

Flashcard 71: For $N_2(g) + O_2(g) \rightleftharpoons 2NO(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[NO]^2}{[N_2][O_2]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 72: What is the effect on $K_c$ if the temperature increases for an endothermic reaction?

Answer: $K_c$ increases. Higher temperature favors endothermic direction (products).

Flashcard 73: What is true about the equilibrium constant when a reaction reaches equilibrium?

Answer: The rate of the forward and reverse reactions are equal. At equilibrium, the equilibrium constant value remains constant.

Flashcard 74: What is the expression for $K_c$ for the decomposition of $H_2O(g)$ into $H_2(g)$ and $O_2(g)$?

Answer: $K_c = \frac{[H_2]^2[O_2]}{[H_2O]^2}$. Decomposition: $2H_2O(g) \rightleftharpoons 2H_2(g) + O_2(g)$.

Flashcard 75: What is the relationship between $K_p$ and $K_c$?

Answer: $K_p = K_c(RT)^{\Delta n}$. $\Delta n$ is the change in moles of gas in the reaction.

Flashcard 76: What will happen to $K_c$ if the equation coefficients are doubled?

Answer: $K_c$ is squared. When coefficients are multiplied by $n$, $K$ is raised to the $n$th power.

Flashcard 77: What is the $K_c$ expression for $CO(g) + 2H_2(g) \rightleftharpoons CH_3OH(g)$?

Answer: $K_c = \frac{[CH_3OH]}{[CO][H_2]^2}$. Products over reactants, each raised to stoichiometric coefficients.

Flashcard 78: State how $K_c$ is affected by a change in concentration.

Answer: $K_c$ is unaffected. Equilibrium constant is independent of concentration changes.

Flashcard 79: What is the $K_c$ expression for the reaction $2H_2(g) + O_2(g) \rightleftharpoons 2H_2O(g)$?

Answer: $K_c = \frac{[H_2O]^2}{[H_2]^2[O_2]}$. Products over reactants, each raised to stoichiometric coefficients.

Flashcard 80: For the reaction $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[NH_3]^2}{[N_2][H_2]^3}$. Products over reactants, each raised to their stoichiometric coefficients.

Flashcard 81: What is the effect on $K_c$ if the temperature decreases for an endothermic reaction?

Answer: $K_c$ decreases. Lower temperature shifts endothermic equilibrium toward reactants.

Flashcard 82: What does a large $K_c$ value indicate about the position of equilibrium?

Answer: The equilibrium favors products. Large $K$ means products are more abundant at equilibrium.

Flashcard 83: For the reaction $A \rightleftharpoons B$, if $K_c = 1$, what does this indicate?

Answer: The concentrations of products and reactants are equal. $K_c = 1$ means equal concentrations of A and B at equilibrium.

Flashcard 84: For the equilibrium $PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[PCl_3][Cl_2]}{[PCl_5]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 85: If $K_p = 5$ and $K_c = 5$ for a reaction, what is $\triangle n$?

Answer: $\triangle n = 0$. When $K_p = K_c$, the change in gas moles is zero.

Flashcard 86: State the relationship between $K_c$ and the rate constants $k_f$ and $k_r$ for a reaction.

Answer: $K_c = \frac{k_f}{k_r}$. Ratio of forward to reverse rate constants equals equilibrium constant.

Flashcard 87: What is true about the equilibrium constant when a reaction reaches equilibrium?

Answer: The rate of the forward and reverse reactions are equal. At equilibrium, the equilibrium constant value remains constant.

Flashcard 88: For $N_2(g) + O_2(g) \rightleftharpoons 2NO(g)$, write the $K_c$ expression.

Answer: $K_c = \frac{[NO]^2}{[N_2][O_2]}$. Products over reactants, raised to stoichiometric coefficients.

Flashcard 89: What is the expression for the equilibrium constant $K_c$ for the reaction $aA + bB \rightleftharpoons cC + dD$?

Answer: $K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}$. Products raised to coefficients over reactants raised to coefficients.