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Questions and Answers
The change in free energy can be expressed as ΔG = ΔH + TΔS.
False
A reaction that proceeds toward equilibrium results in an increase in entropy, making ΔS positive.
True
Electrophiles are functional groups rich in electrons that donate them.
False
At equilibrium, the standard free-energy change ΔGreaction is always greater than zero.
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The standard free-energy changes for reactions can be added together.
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The equilibrium constant Keq for a reaction can be represented as Keq = [A][B]/[C][D].
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Nucleophiles are electron-deficient functional groups that seek electrons.
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The relationship between standard free-energy change and equilibrium constant is given by ΔG = -RT ln K.
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The first law of thermodynamics states that energy can be created but not destroyed.
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A negative ΔG value indicates that a reaction is spontaneous and proceeds in the forward direction.
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The second law of thermodynamics states that the total amount of usable energy in the universe remains constant.
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ΔH represents the total energy of a system, which is equal to free energy G and entropy S.
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Autotrophs are organisms that produce their own energy through photosynthesis or chemosynthesis.
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If Keq is less than 1, the reaction proceeds spontaneously in the forward direction.
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Oxidation-reduction reactions are not involved in the flow of electrons in biological systems.
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Enthalpy change (ΔH) is calculated as the difference between the enthalpy of products and the enthalpy of reactants.
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Study Notes
Bioenergetics
- The study of energy transductions in living cells
- Branch of biochemistry concerned with energy transformation and enzyme function in living systems
Electron Flow
- Provides energy for organisms
- Autotrophs: Obtain energy from inorganic sources
- Heterotrophs: Obtain energy from organic sources
- Electron flow occurs through oxidation-reduction reactions
Laws of Thermodynamics
- First Law: Energy cannot be created or destroyed, only transformed
- Second Law: Systems tend towards equilibrium. Useful energy degrades into useless entropy.
- Enthalpy (H): Total energy of a system
- Free Energy (G): Usable energy
- Entropy (S): Unusable energy
Free Energy and Equilibrium
- Gibbs Free Energy (ΔG): Determines the spontaneity of a reaction
- Equilibrium Constant (Keq): Indicates the direction of reaction
- Keq > 1: Reaction proceeds spontaneously to the right (forward)
- ΔG is negative
- Reaction releases energy
- Keq < 1: Reaction proceeds spontaneously to the left (reverse)
- ΔG is positive
- Reaction requires energy input
Chemical Reactions
- Nucleophiles: Electron-rich functional groups that donate electrons
- Electrophiles: Electron-deficient functional groups that seek electrons
Standard Free Energy Change (ΔG°)
- Free energy change under standard conditions (pH 7, 298 K, 1 atm, 1M concentration)
- Directly related to the equilibrium constant
- ** ΔG° = - RT ln K
- ** R is the gas constant, T is the temperature in Kelvin, and K is the equilibrium constant.
- ** K is a ratio of products to reactants at equilibrium.
Standard Free-Energy Changes and Equilibrium Constants
- Standard free-energy changes (ΔG°) are additive
- Equilibrium Constants (Keq) are multiplicative.
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Description
Test your knowledge on bioenergetics, electron flow, and the laws of thermodynamics. This quiz covers key concepts including Gibbs Free Energy, equilibrium, and energy transformations in living systems. Dive into the principles that govern energy in biological processes.
