Thermodynamics

Question 1

Bioenergetics:

Answer 1

quantitative analysis of how organisms gain and use E

Question 2

Systems are…

Answer 2

what we are studying

- has to have defined boundaries

Question 3

Types of systems:

Answer 3

• open
• isolated
• closed

Question 4

Open system is…

Answer 4

able to exchange both E and matter

Question 5

Isolated system is…

Answer 5

unable to exchange E and matter with surrounding

Question 6

Closed system is…

Answer 6

able to exchange E but not matter

Question 7

Internal E consists of…

Answer 7

• kinetic E of motion
• E of rotation
• E of vibration
• E stored in chemical bonds
• E of non-covalent interactions between molecules

Question 8

T/F: internal E is a function of state of a system

Answer 8

T

Question 9

States of system are defined by..

Answer 9

• temp
• pressure
• volume

Question 10

State functions does not depend on…

Answer 10

the pathway the system took

- only depends on current state of system

Question 11

Examples of state functions:

Answer 11

• internal E
• enthalpy
• entropy
• Gibbs free E

Question 12

Process functions depend on…

Answer 12

pathway between 2 equilibrium states

Question 13

Examples of process functions:

Answer 13

• temp
• heat
• work

Question 14

Work can’t be a state function b/c…

Answer 14

it’s proportional to distance object is moved

Question 15

Changes in internal E of the system and its surroundings is accomplished by…

Answer 15

• heat transfer to and from system

- work on its surrounding from surroundings

Question 16

Examples of work forms:

Answer 16

• expansion of system against pressure
• expansion against surface tension
• contraction of muscle

Question 17

Heat (q):

Answer 17

(+) q = heat absorbed by system

(-) q = heat given off to surroundings

Question 18

Work (w):

Answer 18

(+) w = work done by system

(-) w = work done on system by surroundings

Question 19

First law of thermodynamics:

Answer 19

E can’t be created or destroyed

delta E = q - w (path independent)

Question 20

Ideal gas law:

Answer 20

PV=nRT

Question 21

Enthalpy (H) is a ______ function

Answer 21

state

Question 22

What contributes to enthalpy?

Answer 22

• work

- heat

Question 23

T/F: delta H = delta E

Answer 23

T b/c volume changes are small in biochem

Question 24

Formula for H at constant pressure:

Answer 24

delta H = delta E + P(delta V)

Question 25

Second law of thermodynamics:

Answer 25

entropy of isolated system will tend to increase to max value

Question 26

Entropy (S) is the relative degree of...

Answer 26

disorder measured by a state function

Question 27

Formula for entropy:

Answer 27

S = klnW (k=boltzmann constant)

Question 28

Positive entropy contributions are increased...

Answer 28

- motions - rotations - degrees of freedom - particle # - disorder based on state of matter - number of molecules - spatial distribution of molecules/particles

Question 29

An open system needs a function of both...

Answer 29

- entropy | - enthalpy

Question 30

Gibbs free E (G):

Answer 30

state function that combines both entropy and enthalpy

Question 31

Gibbs free E formula:

Answer 31

delta G = delta H - T(delta S)

Question 32

Exergonic:

Answer 32

thermodynamically favorable (-delta G)

Question 33

Endergonic:

Answer 33

thermodynamically unfavorable (+delta G)

Question 34

If delta G = 0, then system is...

Answer 34

in equilibrium

Question 35

At low T, delta H dominates and delta G is...

Answer 35

positive

Question 36

At high T, T(delta S) dominates and delta G is...

Answer 36

negative

Question 37

(-) delta H and (+) delta S =

Answer 37

spontaneous (-delta G)

Question 38

(-) delta H and (-) delta S =

Answer 38

spontaneous only at low temp

Question 39

(+) delta H and (+) delta S =

Answer 39

spontaneous only at high temp

Question 40

(+) delta H and (-) delta S =

Answer 40

unspontaneous

Question 41

How to calculate free E:

Answer 41

delta G = G(prod) - G(reactants)

Question 42

Standard free E change:

Answer 42

- delta G = RTlnK | K = e^(- delta G/RT)

Question 43

T/F: unfavorable reactions will never be favorable

Answer 43

F, can be made thermodynamically favorable by coupling them to favored reactions

Question 44

High E compounds are compounds w/...

Answer 44

large negative free E changes

Question 45

Examples of high E compounds:

Answer 45

- phosphate anhydrides - enol phosphates - thioesters - compounds containing N-P bonds

Question 46

Hydrolysis of ATP is...

Answer 46

highly exergonic | - delta standard free E = -31 kj/mol

Question 47

Why is hydrolytic release of phosphate high in E?

Answer 47

- resonance stabilization of phosphate products - electrostatic repulsion between charged products - tautomerization - release of proton in buffered solution (pH influences equilibrium)