Gibbs Free Energy and Thermodynamic Favorability
Sophie Anderson
7 min read
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Study Guide Overview
This study guide covers thermodynamic favorability and spontaneity of reactions. Key concepts include enthalpy (ΔH°), entropy (ΔS°), and Gibbs Free Energy (ΔG°). It explains how to calculate ΔG° using the formula ΔG° = ΔH° - TΔS° and standard free energies of formation. The guide also discusses conditions influencing spontaneity and distinguishes between entropy-driven and enthalpy-driven reactions, including practice problems and exam tips.
#Thermodynamic Favorability: Is It Going to Happen? 🤔
Hey, future AP Chem master! Let's dive into thermodynamic favorability, which is all about predicting whether a reaction will occur spontaneously. Think of it like this: is the reaction naturally inclined to happen, or does it need a push? Let's find out!
This topic is crucial for understanding reaction spontaneity and equilibrium, which are major themes in AP Chemistry. Expect to see these concepts in both multiple-choice and free-response questions.
#Explaining Thermodynamic Favorability
Thermodynamic favorability helps us determine if a reaction is spontaneous (happens on its own) or nonspontaneous (needs external help). Spontaneous reactions are thermodynamically favorable, while non-spontaneous ones are thermodynamically unfavorable.
Spontaneity is directly linked to the equilibrium constant. A spontaneous reaction tends to favor product formation.
#Enthalpy (ΔH°) and Entropy (ΔS°): The Dynamic Duo
Two main factors determine spontaneity:
- Enthalpy Change (ΔH°): This is the heat change in a reaction.
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Exothermic (ΔH° < 0): System loses heat to surroundings. Think of it as 'heat exiting'. 🔥
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Endothermic (ΔH° > 0): System gains heat from surroundings. Think of it as 'heat entering'. 🧊
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*Caption: Visualizing exothermic and endothermic reactions. Exothermic reactions release heat, while endothermic reactions absorb it.*
2. Entropy Change (ΔS°): This is the change in disorder or randomness of a system. * Positive ΔS°: Disorder increases. More chaos! 🎉 * Negative ΔS°: Disorder decreases. More order. 😥
Reactions that increase entropy are exentropic, and those that decrease entropy are endentropic. These terms are less common on the AP exam but good to know. ...
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