Bioenergetics

Question 1

what is enthalpy?

Answer 1

a function related to heat transfer and work expenditure in the system

Question 2

what is ΔH?

Answer 2

change in Enthalpy

Question 3

negative ΔH implies?

Answer 3

heat is lost by the system

Question 4

positive ΔH implies?

Answer 4

heat is gained by the system

Question 5

negative ΔH favorable or unfavorable? exothermic or endothermic?

Answer 5

favorable; exothermic

Question 6

positive ΔH favorable or unfavorable? exothermic or endothermic?

Answer 6

unfavorable; endothermic

Question 7

an ordered state is low or high entropy?

Answer 7

low

Question 8

a disordered state is high or low?

Answer 8

high

Question 9

increase or decrease in entropy is always favored?

Answer 9

increase

Question 10

what is ΔS?

Answer 10

change in Entropy

Question 11

what does negative ΔS mean?

Answer 11

the system has become more ordered

Question 12

what does positive ΔS mean?

Answer 12

the system has become less ordered

Question 13

is negative ΔS favored or unfavored?

Answer 13

unfavored

Question 14

is positive ΔS favored or unfavored?

Answer 14

favored

Question 15

is negative ΔS ordered or disordered?

Answer 15

ordered

Question 16

is positive ΔS ordered or disordered?

Answer 16

disordered

Question 17

what is free energy?

Answer 17

tells how much energy is available for work and…

…allows one to asses reaction spontaneity (i.e., probability)

ΔG =ΔH - TΔS (constant temperature)

Question 18

is a decrease in free energy favorable or unfavorable?

Answer 18

favorable

Question 19

The change in free energy for a reaction depends on many factors, like?

Answer 19

(concentration of reactants, pH, temperature, pressure)

Question 20

what is ΔG?

Answer 20

change in spontaneity

Question 21

what is negative ΔG?

Answer 21

the system has decreased in free energy

Question 22

what is positive ΔG?

Answer 22

the system has increased in free energy

Question 23

negative ΔG is exergonic or endergonic?

Answer 23

exergonic, energy is released

Question 24

positive ΔG is exergonic or endergonic?

Answer 24

endergonic, energy is required

Question 25

is negative ΔG favorable or unfavorable?

Answer 25

favorable

negative ΔH, large positive ΔS, or both

note equation

ΔG = G2 – G1 = ΔH - TΔS

Question 26

is positive ΔG favorable or unfavorable?

Answer 26

unfavorable

positive ΔH, negative or small ΔS, or both

note equation

ΔG = G2 – G1 = ΔH - TΔS

Question 27

noting the equation:

A + B ↔ C + D
ΔG = ΔH - TΔS

what happens if ΔG=0

Answer 27

reaction is at equilibrium

Question 28

noting the equation:

A + B ↔ C + D
ΔG = ΔH - TΔS

what happens if ΔG<0

Answer 28

reaction proceeds as written to favor C and D formation

Called “spontaneous”

Question 29

noting the equation:

A + B ↔ C + D
ΔG = ΔH - TΔS

what happens if ΔG>0

Answer 29

reaction proceeds opposite to that written to favor A and B formation
Called “non-spontaneous”

Question 30

How can we calculate the free energy change for reactions not at standard state?

Answer 30

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

Question 31

If Keq < 1, ln Keq is? ΔGo’ is?

Answer 31

positive A and B are favored over C and D

Question 32

If Keq > 1, ln Keq is? ΔGo’ is?

Answer 32

negative C and D are favored over A and B

Question 33

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?

Answer 33

products, C and D are favored

Question 34

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?

Answer 34

reactants, A and B are favored