Bioenergetics Flashcards
what is enthalpy?
a function related to heat transfer and work expenditure in the system
what is ΔH?
change in Enthalpy
negative ΔH implies?
heat is lost by the system
positive ΔH implies?
heat is gained by the system
negative ΔH favorable or unfavorable? exothermic or endothermic?
favorable; exothermic
positive ΔH favorable or unfavorable? exothermic or endothermic?
unfavorable; endothermic
an ordered state is low or high entropy?
low
a disordered state is high or low?
high
increase or decrease in entropy is always favored?
increase
what is ΔS?
change in Entropy
what does negative ΔS mean?
the system has become more ordered
what does positive ΔS mean?
the system has become less ordered
is negative ΔS favored or unfavored?
unfavored
is positive ΔS favored or unfavored?
favored
is negative ΔS ordered or disordered?
ordered
is positive ΔS ordered or disordered?
disordered
what is free energy?
tells how much energy is available for work and…
…allows one to asses reaction spontaneity (i.e., probability)
ΔG =ΔH - TΔS (constant temperature)
is a decrease in free energy favorable or unfavorable?
favorable
The change in free energy for a reaction depends on many factors, like?
(concentration of reactants, pH, temperature, pressure)
what is ΔG?
change in spontaneity
what is negative ΔG?
the system has decreased in free energy
what is positive ΔG?
the system has increased in free energy
negative ΔG is exergonic or endergonic?
exergonic, energy is released
positive ΔG is exergonic or endergonic?
endergonic, energy is required
is negative ΔG favorable or unfavorable?
favorable
negative ΔH, large positive ΔS, or both
note equation
ΔG = G2 – G1 = ΔH - TΔS
is positive ΔG favorable or unfavorable?
unfavorable
positive ΔH, negative or small ΔS, or both
note equation
ΔG = G2 – G1 = ΔH - TΔS
noting the equation:
A + B ↔ C + D
ΔG = ΔH - TΔS
what happens if ΔG=0
reaction is at equilibrium
noting the equation:
A + B ↔ C + D
ΔG = ΔH - TΔS
what happens if ΔG<0
reaction proceeds as written to favor C and D formation
Called “spontaneous”
noting the equation:
A + B ↔ C + D
ΔG = ΔH - TΔS
what happens if ΔG>0
reaction proceeds opposite to that written to favor A and B formation
Called “non-spontaneous”
How can we calculate the free energy change for reactions not at standard state?
ΔG = ΔGo’ + RT ln [C][D]/[A][B]
Products divided by reactants, which is favored is based on size, i.e., so if C and D is large than products are favored and delta G is less than one
If Keq < 1, ln Keq is? ΔGo’ is?
positive A and B are favored over C and D
If Keq > 1, ln Keq is? ΔGo’ is?
negative C and D are favored over A and B
noting the equations;
A + B ↔ C + D
Keq = [C][D]/[A][B]
ΔGo’ = - RT ln Keq
If ΔG = 0, reaction is at equilibrium (no net change in [A], [B], [C] or [D])
Then:
ΔGo’ < 0, ln Keq > 1,
are products or reactants favored?
products, C and D are favored
noting the equations;
A + B ↔ C + D
Keq = [C][D]/[A][B]
ΔGo’ = - RT ln Keq
If ΔG = 0, reaction is at equilibrium (no net change in [A], [B], [C] or [D])
Then:
ΔGo’ > 0, ln Keq < 1,
are products or reactants favored?
reactants, A and B are favored
