Lecture 3: Energy, Entropy, and Complexity Flashcards
Energy is the ability to produce ___1__, whereas heat is the flow of ___2__ which increases random motion/vibration of molecules
1) change
2) energy
What is work?
W = Force(F) x distance(d)
It is the flow of energy which causes directional, non-random change in a system
Gibbs Free Energy (G) is a measure of how far a system is away from ___1___ and is the amount of energy that is “free” to do __2___
1) equillibrium
2) work
Distinguish enthalpy from entropy
enthalpy (H) is the chemical potential energy plus kindetic energy of random thermal motion; exothermic rxn heat is release and endothermic rxn heat is absorbed
entropy (S) is the measure of randomness, disorder, and dispersion of energy; when S is positive it means there is an increase in randomness/disorder during a rxn or process. when S is negative there is a decrease in randomness/disorder
A system at ______ is in its state of lowest free energy (most stable state)
equillibrium
Distinguish between ∆G and ∆G’˚
∆G’˚ is the standard free energy change, which is a constant for a given rxn/process based on standard conditions
∆G is a constant that will vary depending on concentrations, temperatures, etc.
What is the chemical standard state?
25˚C (298K), 1 atm, initial concentrations (reactants and products) = 1 M
The biochemical standard state: 25˚C (298K), 1 atm, initial concentrations (reactants and products) = 1 M EXCEPT [H+] = 10^-7M (pH = 7), [H2O] = 55.5 M, [Mg2+] = 1mM
How is Q related to K’eq?
Q tells you how far away the system is from equilibrium; it is the mass actions expression for initial conditions
K’eq = mass action expression for equilibrium conditions
What is the ∆G equation that involves initial concentrations, temperature, and ∆G’˚
∆G = RT ln Q + ∆G’˚
∆G’˚ = - RT ln K’eq
therefore ∆G can also be written as:
∆G = RTlnQ - RTlnK’eq
Why is it important to consider the standard free energy change (∆G’˚) and actual free energy change (∆G) under physiologic conditions?
Because the free energy value will change depending on the conditions the reaction is taking place in. i.e. the hydrolysis of ATP in a erythrocyte has a standard free energy of -30.5 kJ/mol, but under physiologic conditions, the actual free energy change is -52kJ/mol. Hence, under physiologic conditions, this reaction releases even more energy than predicted by the standard free energy.
Name whether the following conditions means whether the forward or reverse reaction is thermodynamically favored, or if the system is at equilibrium:
1) Q < K’eq
2) Q = K’eq
3) Q > K’eq
1) Q < K’eq, ∆G < 0; forward direction is thermodynamically favored
2) Q = K’eq, ∆G = 0, system is at equilibrium
3) Q > K’eq, ∆G > 0; reverse direction is thermodynamically favored
Are systems at equilibrium capable of doing any work?
no, because no energy is flowing in or out (there is no net change in concentrations)
Do living systems operate at equilibrium? Why or why not?
No. because systems at equilibrium cannot do any work, and living systems must be able to do work.
Differentiate between equilibrium and homeostasis
both refer to systems of balance and is the most stable state of that particular system
The difference between the two equilibrium, there is no energy flowing in or out of the system. At homeostasis, energy is flowing in and out of the system (hence it is an open system), but the flow of that energy is balanced and constant. Thus, homeostasis is a non-equillibrium steady state
What is the first law of thermodynamics?
conservation of energy: energy can’t be created or destroyed, but can only be changed from one form to another (transduction)
