AP Chemistry Flashcards: Endothermic And Exothermic Processes

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This deck focuses on Endothermic And Exothermic Processes, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

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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: State Hess's Law.

Answer: The total enthalpy change is the same no matter how the reaction is carried out. Enthalpy is path-independent, only depends on states.

Flashcard 2: What is a non-spontaneous process?

Answer: A process that requires continuous external energy input. Thermodynamically unfavorable without energy input.

Flashcard 3: What is the standard state condition for enthalpy changes?

Answer: 1 atm pressure and 298 K temperature. Reference conditions for thermodynamic measurements.

Flashcard 4: Which type of reaction is combustion?

Answer: Combustion is an exothermic reaction. Burning reactions always release energy.

Flashcard 5: State the First Law of Thermodynamics.

Answer: Energy cannot be created or destroyed, only transformed. Conservation of energy principle in thermodynamics.

Flashcard 6: Identify whether the rusting of iron is endothermic or exothermic.

Answer: Rusting of iron is exothermic. Oxidation reactions release energy.

Flashcard 7: What is meant by a spontaneous process?

Answer: A process that occurs without external energy input. Thermodynamically favorable under given conditions.

Flashcard 8: State the enthalpy change for an exothermic reaction.

Answer: $\triangle H$ is negative. Energy is released during the reaction.

Flashcard 9: State the enthalpy change for an endothermic reaction.

Answer: $\triangle H$ is positive. Energy is absorbed during the reaction.

Flashcard 10: What is the sign of $\triangle H$ for a reaction that releases heat?

Answer: The sign of $\triangle H$ is negative. Heat release means negative enthalpy change.

Flashcard 11: Identify an endothermic process in everyday life.

Answer: Photosynthesis is an endothermic process. Light energy is absorbed to drive the reaction.

Flashcard 12: Define enthalpy ($H$) in thermodynamics.

Answer: Enthalpy is the total heat content of a system. It's a state function measuring internal energy.

Flashcard 13: Is dissolving ammonium nitrate in water endothermic or exothermic?

Answer: It is an endothermic process. Dissolution breaks ionic bonds, absorbing energy.

Flashcard 14: Calculate $\triangle H$: Reactants = 200 kJ, Products = 150 kJ.

Answer: $\triangle H = 150 - 200 = -50$ kJ. Products have lower energy than reactants.

Flashcard 15: Which phase change is endothermic: melting or freezing?

Answer: Melting is endothermic. Energy is needed to break intermolecular forces.

Flashcard 16: What is the sign of $\triangle H$ for a reaction that absorbs heat?

Answer: The sign of $\triangle H$ is positive. Heat absorption means positive enthalpy change.

Flashcard 17: What is meant by activation energy?

Answer: The minimum energy required to initiate a reaction. Energy barrier that must be overcome.

Flashcard 18: What does a calorimeter measure?

Answer: A calorimeter measures the heat of chemical reactions. Device that quantifies energy changes in reactions.

Flashcard 19: What is the heat of reaction?

Answer: The heat absorbed or released during a chemical reaction. Energy change when reactants become products.

Flashcard 20: What does a positive $\triangle H$ indicate about heat flow?

Answer: Heat is absorbed by the system. System gains energy from surroundings.

Flashcard 21: Identify whether the evaporation of alcohol is endothermic or exothermic.

Answer: Evaporation of alcohol is endothermic. Phase change requires energy input.

Flashcard 22: Identify whether lighting a match is endothermic or exothermic.

Answer: Lighting a match is exothermic. Combustion of match head releases energy.

Flashcard 23: Identify whether boiling water is endothermic or exothermic.

Answer: Boiling water is an endothermic process. Energy is required to overcome intermolecular forces.

Flashcard 24: What is the standard state condition for enthalpy changes?

Answer: 1 atm pressure and 298 K temperature. Reference conditions for thermodynamic measurements.

Flashcard 25: Which type of reaction is combustion?

Answer: Combustion is an exothermic reaction. Burning reactions always release energy.

Flashcard 26: Differentiate between system and surroundings in thermodynamics.

Answer: The system is the part of the universe being studied; surroundings are everything else. Defines boundaries for energy transfer analysis.

Flashcard 27: What is meant by activation energy?

Answer: The minimum energy required to initiate a reaction. Energy barrier that must be overcome.

Flashcard 28: Identify whether freezing water is endothermic or exothermic.

Answer: Freezing water is an exothermic process. Energy is released as molecules form ordered structure.

Flashcard 29: State the enthalpy change for an endothermic reaction.

Answer: $\triangle H$ is positive. Energy is absorbed during the reaction.

Flashcard 30: What is the sign of $\triangle H$ for a reaction that releases heat?

Answer: The sign of $\triangle H$ is negative. Heat release means negative enthalpy change.