AP Chemistry Flashcards: Free Energy And Equilibrium

What this deck covers

This deck focuses on Free Energy And 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: Determine the sign of $\triangle G$ for a process at equilibrium.

Answer: $\triangle G = 0$. At equilibrium, there is no net change in free energy.

Flashcard 2: Which term describes a reaction with $\triangle H > 0$?

Answer: Endothermic. Positive enthalpy change indicates heat is absorbed from surroundings.

Flashcard 3: What is the effect of increasing temperature on an endothermic reaction's equilibrium position?

Answer: Shifts to the right (toward products). Higher temperature favors the endothermic direction according to Le Châtelier's principle.

Flashcard 4: What happens to the equilibrium constant $K$ as temperature increases for an exothermic reaction?

Answer: $K$ decreases. Higher temperature disfavors exothermic reactions, reducing $K$.

Flashcard 5: What condition is necessary for a reaction to be at equilibrium in terms of $Q$ and $K$?

Answer: $Q = K$. At equilibrium, the reaction quotient equals the equilibrium constant.

Flashcard 6: State the equation relating Gibbs free energy and reaction quotient $Q$.

Answer: $\triangle G = \triangle G^\text{°} + RT \text{ln}Q$. This equation relates free energy to reaction progress via quotient $Q$.

Flashcard 7: What is the effect of increasing volume on the equilibrium of a gaseous reaction?

Answer: Shifts toward more moles of gas. Larger volume favors the side with more gas molecules.

Flashcard 8: What is the effect of increasing temperature on an exothermic reaction's equilibrium position?

Answer: Shifts to the left (toward reactants). Higher temperature opposes the exothermic direction per Le Châtelier's principle.

Flashcard 9: Which term describes a reaction with $\triangle H > 0$?

Answer: Endothermic. Positive enthalpy change indicates heat is absorbed from surroundings.

Flashcard 10: What is the term for the energy required to break bonds in reactants?

Answer: Bond dissociation energy. Energy input needed to break existing chemical bonds in reactants.

Flashcard 11: What is the meaning of Gibbs free energy being state function?

Answer: Depends only on initial and final states. State functions are path-independent, only depending on endpoints.

Flashcard 12: What is the significance of $\triangle G = 0$?

Answer: The system is at equilibrium. At equilibrium, forward and reverse reaction rates are equal.

Flashcard 13: What does the term 'entropy' refer to in thermodynamics?

Answer: The measure of disorder or randomness. Entropy quantifies the number of possible microstates in a system.

Flashcard 14: What does the term 'enthalpy' refer to in thermodynamics?

Answer: The total heat content of a system. Enthalpy represents the total energy stored in chemical bonds.

Flashcard 15: Identify the units for Gibbs free energy change, $\triangle G$.

Answer: Joules (J). Energy units match the dimensions of enthalpy and entropy terms.

Flashcard 16: What is the significance of the equilibrium constant $K$ being less than 1?

Answer: Reactants are favored at equilibrium. Small $K$ values indicate equilibrium lies toward the reactant side.

Flashcard 17: What is the effect of a common ion on the solubility of a salt?

Answer: Decreases solubility. Common ion effect shifts equilibrium by Le Châtelier's principle.

Flashcard 18: Which term describes a reaction with $\triangle H > 0$?

Answer: Endothermic. Positive enthalpy change indicates heat is absorbed from surroundings.

Flashcard 19: What does a negative $\triangle G$ indicate about a reaction?

Answer: The reaction is spontaneous. Negative $\triangle G$ means the process proceeds forward without external energy.

Flashcard 20: What is the value of $R$ in the equation $\triangle G = -RT \text{ln}K$?

Answer: $8.314 \text{ J/mol·K}$. Universal gas constant used in thermodynamic calculations.

Flashcard 21: What is the effect of increasing pressure on the equilibrium of a gaseous reaction?

Answer: Shifts toward fewer moles of gas. Higher pressure favors the side with fewer gas molecules.

Flashcard 22: What happens to the equilibrium constant $K$ as temperature increases for an endothermic reaction?

Answer: $K$ increases. Higher temperature favors endothermic reactions, increasing $K$.

Flashcard 23: What is the relationship between Gibbs free energy and reaction spontaneity?

Answer: Negative $\triangle G$ indicates spontaneity. The sign of $\triangle G$ determines if a reaction proceeds spontaneously.

Flashcard 24: What is the effect of adding a catalyst on the equilibrium position?

Answer: No effect on equilibrium position. Catalysts speed up both forward and reverse reactions equally.

Flashcard 25: What does a positive $\triangle G$ indicate about a reaction?

Answer: The reaction is non-spontaneous. Positive $\triangle G$ means external energy is required for the process to occur.

Flashcard 26: Which thermodynamic quantity is directly related to the spontaneity of a process?

Answer: Gibbs free energy, $\triangle G$. Gibbs free energy determines whether reactions proceed spontaneously.

Flashcard 27: How does the addition of an inert gas at constant volume affect equilibrium?

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

Flashcard 28: Which term describes a reaction with $\triangle H < 0$?

Answer: Exothermic. Negative enthalpy change indicates heat is released to surroundings.

Flashcard 29: State the relationship between $\triangle G^\text{°}$ and $K$ for a reaction at equilibrium.

Answer: $\triangle G^\text{°} = -RT \text{ln}K$. Standard free energy change relates directly to equilibrium constant.

Flashcard 30: Identify the units commonly used for entropy, $S$.

Answer: Joules per Kelvin (J/K). Entropy has units of energy per temperature unit.

Flashcard 31: What is the significance of the equilibrium constant $K$ being greater than 1?

Answer: Products are favored at equilibrium. Large $K$ values indicate equilibrium lies toward the product side.

Flashcard 32: What does Le Châtelier's principle predict?

Answer: How a system at equilibrium responds to changes. Le Châtelier's principle describes equilibrium shifts to counteract disturbances.

Flashcard 33: Identify the condition under which a reaction is at dynamic equilibrium.

Answer: Rate of forward and reverse reactions are equal. Dynamic equilibrium means constant concentrations with ongoing reactions.

Flashcard 34: What is the effect of decreasing temperature on an exothermic reaction's equilibrium position?

Answer: Shifts to the right (toward products). Lower temperature favors the exothermic direction per Le Châtelier's principle.

Flashcard 35: State the equation relating $\triangle G$ and equilibrium constant $K$.

Answer: $\triangle G = -RT \text{ln}K$. This equation connects thermodynamics ($\triangle G$) to kinetics ($K$).