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What is thermodynamics?
The set of laws that describe how energy and matter behave at a macroscopic level.
An enzyme would _____ the reaction but wouldn't affect the ______.
speed up, equilibrium
What does it mean that energy is a state function?
Energies of reactants to products are independent of the conversion pathway.
What is ΔH in a reaction?
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If ΔH is 0, heat is ______, and the reaction is ______.
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What is entropy?
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What contributes to the entropy of a molecule?
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As temperature increases, how does entropy change?
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Match the following concepts regarding biological processes:
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What is the relationship of enthalpy and entropy in spontaneous reactions?
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What is Gibbs Free Energy change?
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Is an exergonic reaction characterized by ΔG < 0?
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Is an endergonic reaction characterized by ΔG > 0?
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At equilibrium, ΔG = ______.
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What is the significance of ΔH (-) and ΔS (+)?
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What occurs when ΔS > 0?
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What is the relationship between Gibbs Free Energy and coupled reactions?
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What is ATP's role in coupled reactions?
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The equation for the transport of uncharged molecules is ΔG = ______.
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What is the significance of electric potential difference in the transport of charged molecules?
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Study Notes
Thermodynamics Overview
- Thermodynamics describes energy and matter behavior at the macroscopic level.
- It predicts the macroscopic properties of chemical reactions, indicating direction and equilibrium but not reaction speed.
Enzymatic Influence
- Enzymes speed up reactions but do not affect the equilibrium position.
Energy as a State Function
- The energy change in a reaction is independent of the conversion pathway.
- At equilibrium, the ratio of reactants to products remains consistent regardless of the mechanism.
Enthalpy
- Enthalpy change (ΔH) represents the heat generated or absorbed during a reaction: ΔH = Hproducts - Hreactants.
- A positive ΔH indicates absorbed heat, defining the reaction as endothermic.
Entropy
- Entropy measures disorder; the universe tends towards increased disorder and is also a state function.
- The entropy of a molecule includes contributions from translational, rotational, and internal motions.
Entropy and Molecular Interactions
- Condensation of two molecules into one costs translational and rotational entropy.
- Increased temperature typically results in higher system entropy.
Biological Processes
- Biological systems balance entropy and enthalpy to drive reactions.
Entropic and Enthalpic Processes
- Examples include DNA strand association (entropy decrease) and the hydrophobic effect (entropy increase).
Reaction Spontaneity
- Determining reaction spontaneity requires both enthalpy and entropy considerations.
- Gibbs Free Energy (G) combines both: ΔG = ΔH - TΔS.
Gibbs Free Energy
- A negative ΔG indicates a spontaneous reaction; stability of products over substrates is key.
- Factors influencing ΔG are enthalpy (ΔH) and entropy (ΔS).
Reaction Types
- Exergonic: ΔG < 0 (spontaneous, can be endothermic or exothermic).
- Endergonic: ΔG > 0 (not spontaneous, reverse reaction may be spontaneous).
- Equilibrium: ΔG = 0 (no net reaction).
Temperature Effects on Reactions
- Reactions with ΔH (-), ΔS (+) are spontaneous at all temperatures.
- Reactions with ΔH (-), ΔS (-) can be spontaneous only below a specific temperature.
- Reactions with ΔH (+), ΔS (+) are spontaneous above a certain temperature, while those with both ΔH (+) and ΔS (-) are unspontaneous.
Entropy Increase with Temperature
- The TΔS term grows larger as temperature rises, influencing spontaneity.
Coupled Reactions
- An unfavorable reaction can drive a favorable one if the overall ΔG remains less than zero, crucial in metabolic pathways.
ATP as Energy Currency
- ATP hydrolysis is highly exergonic and can drive endergonic reactions, linking energy release and demand.
Transport Dynamics for Molecules
- The transport of uncharged molecules follows the concentration gradient; ΔGo' is zero at equilibrium.
- For charged molecules, the electric potential difference across membranes is significant in determining ΔG, incorporating both concentration and charge.
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Description
Explore the core concepts of thermodynamics through these informative flashcards. Understand the fundamental laws governing energy and matter at a macroscopic level, as well as the influence of enzymes on chemical reactions. Test your knowledge and reinforce your learning in this crucial science field.