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 happens to $K_c$ if the equation is reversed?

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

Flashcard 4: State how $K_c$ is affected by a change in concentration.

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

Flashcard 5: 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 6: 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 7: 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 8: 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 9: 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 10: 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 11: 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 12: 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 13: 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 14: State how $K_c$ is affected by a change in concentration.

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

Flashcard 15: 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 16: 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 17: 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 18: 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 19: 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 20: 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 21: 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 22: 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 23: 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 24: 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 25: 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 26: 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 27: 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 28: 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 29: 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 30: State how $K_c$ is affected by a change in concentration.

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

Flashcard 31: How does changing volume affect $K_c$?

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

Flashcard 32: 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 33: 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 34: 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 35: 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 36: 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 37: 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 38: 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 39: 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 40: 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 41: 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 42: 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 43: 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 44: 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 45: 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 46: 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 47: 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 48: 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 49: 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 50: 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 51: 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 52: 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.