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: Identify an endothermic process in everyday life.

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

Flashcard 2: Identify whether the evaporation of alcohol is endothermic or exothermic.

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

Flashcard 3: Identify whether freezing water is endothermic or exothermic.

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

Flashcard 4: State the relationship between $\triangle H$ and reaction spontaneity.

Answer: $\triangle H$ alone does not determine spontaneity. Gibbs free energy determines spontaneity.

Flashcard 5: State the unit commonly used for enthalpy change.

Answer: The unit is kilojoules per mole (kJ/mol). Standard unit for measuring enthalpy changes.

Flashcard 6: What is the heat of reaction?

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

Flashcard 7: What does a positive $\triangle H$ indicate about heat flow?

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

Flashcard 8: What is a non-spontaneous process?

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

Flashcard 9: Identify the sign of $\triangle H$ for exothermic reactions.

Answer: $\triangle H$ is negative for exothermic reactions. Energy is released, so enthalpy decreases.

Flashcard 10: Identify whether lighting a match is endothermic or exothermic.

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

Flashcard 11: What does a negative $\triangle H$ indicate about heat flow?

Answer: Heat is released by the system. System loses energy to surroundings.

Flashcard 12: What is the standard state condition for enthalpy changes?

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

Flashcard 13: State the First Law of Thermodynamics.

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

Flashcard 14: What does a positive $\triangle H$ indicate about heat flow?

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

Flashcard 15: What is the standard state condition for enthalpy changes?

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

Flashcard 16: Which phase change is endothermic: melting or freezing?

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

Flashcard 17: Identify whether the rusting of iron is endothermic or exothermic.

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

Flashcard 18: 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 19: Identify an exothermic process in everyday life.

Answer: Burning wood is an exothermic process. Combustion releases energy as heat and light.

Flashcard 20: Identify the sign of $\triangle H$ for endothermic reactions.

Answer: $\triangle H$ is positive for endothermic reactions. Energy is absorbed, so enthalpy increases.

Flashcard 21: 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 22: 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 23: What is a non-spontaneous process?

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

Flashcard 24: Is dissolving ammonium nitrate in water endothermic or exothermic?

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

Flashcard 25: Identify whether freezing water is endothermic or exothermic.

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

Flashcard 26: Identify an exothermic process in everyday life.

Answer: Burning wood is an exothermic process. Combustion releases energy as heat and light.

Flashcard 27: What is meant by a spontaneous process?

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

Flashcard 28: Which type of reaction is combustion?

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

Flashcard 29: Calculate $\triangle H$: Reactants = 100 kJ, Products = 180 kJ.

Answer: $\triangle H = 180 - 100 = 80$ kJ. Products have higher energy than reactants.

Flashcard 30: Identify an exothermic process in everyday life.

Answer: Burning wood is an exothermic process. Combustion releases energy as heat and light.

Flashcard 31: What is a non-spontaneous process?

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

Flashcard 32: Identify whether baking bread is endothermic or exothermic.

Answer: Baking bread is an endothermic process. Chemical reactions in baking require energy input.

Flashcard 33: State the First Law of Thermodynamics.

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

Flashcard 34: What is an exothermic process?

Answer: A process that releases heat to its surroundings. Heat flows out of the system to the environment.

Flashcard 35: What does a calorimeter measure?

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

Flashcard 36: 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 37: Which type of reaction is combustion?

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

Flashcard 38: Identify whether the rusting of iron is endothermic or exothermic.

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

Flashcard 39: Calculate $\triangle H$: Reactants = 200 kJ, Products = 150 kJ.

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

Flashcard 40: Identify whether freezing water is endothermic or exothermic.

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

Flashcard 41: Which type of reaction is combustion?

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

Flashcard 42: What does a calorimeter measure?

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

Flashcard 43: What is meant by a spontaneous process?

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

Flashcard 44: 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 45: What is the standard state condition for enthalpy changes?

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

Flashcard 46: Identify whether lighting a match is endothermic or exothermic.

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

Flashcard 47: Calculate $\triangle H$: Reactants = 100 kJ, Products = 180 kJ.

Answer: $\triangle H = 180 - 100 = 80$ kJ. Products have higher energy than reactants.

Flashcard 48: Identify whether the rusting of iron is endothermic or exothermic.

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

Flashcard 49: State the enthalpy change for an exothermic reaction.

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

Flashcard 50: Identify if dissolving NaCl in water is endothermic or exothermic.

Answer: Dissolving NaCl in water is endothermic. Ion separation requires energy input.

Flashcard 51: What does a calorimeter measure?

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

Flashcard 52: Identify whether lighting a match is endothermic or exothermic.

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

Flashcard 53: State the enthalpy change for an exothermic reaction.

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

Flashcard 54: Identify whether boiling water is endothermic or exothermic.

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

Flashcard 55: Which phase change is exothermic: condensation or vaporization?

Answer: Condensation is exothermic. Energy is released when gas molecules organize.

Flashcard 56: State the enthalpy change for an endothermic reaction.

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

Flashcard 57: State the First Law of Thermodynamics.

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

Flashcard 58: Identify whether the evaporation of alcohol is endothermic or exothermic.

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

Flashcard 59: What is meant by activation energy?

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

Flashcard 60: What is the heat of reaction?

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

Flashcard 61: What is an endothermic process?

Answer: A process that absorbs heat from its surroundings. Heat flows into the system from the environment.

Flashcard 62: What does a positive $\triangle H$ indicate about heat flow?

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

Flashcard 63: Calculate $\triangle H$: Reactants = 100 kJ, Products = 180 kJ.

Answer: $\triangle H = 180 - 100 = 80$ kJ. Products have higher energy than reactants.

Flashcard 64: 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 65: State the enthalpy change for an endothermic reaction.

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

Flashcard 66: State the enthalpy change for an exothermic reaction.

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

Flashcard 67: 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 68: What is meant by activation energy?

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

Flashcard 69: Identify whether the evaporation of alcohol is endothermic or exothermic.

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

Flashcard 70: Identify whether boiling water is endothermic or exothermic.

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

Flashcard 71: Identify whether boiling water is endothermic or exothermic.

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

Flashcard 72: What is the heat of reaction?

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

Flashcard 73: What does $\triangle H$ represent in thermochemistry?

Answer: $\triangle H$ represents the change in enthalpy. It measures energy changes in chemical reactions.

Flashcard 74: 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 75: Define enthalpy ($H$) in thermodynamics.

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

Flashcard 76: 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 77: What is meant by activation energy?

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

Flashcard 78: Which phase change is exothermic: condensation or vaporization?

Answer: Condensation is exothermic. Energy is released when gas molecules organize.

Flashcard 79: 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 80: What is the heat of formation?

Answer: The change in enthalpy when one mole of a compound is formed. Standard enthalpy for compound synthesis from elements.

Flashcard 81: What is meant by a spontaneous process?

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