Thermodynamics and Gibbs free energy

Question 1

Gibbs free energy (G) occurs

Answer 1

energy transfer happens as w and heat - wanting to know amount of work the reaction produces

Question 2

Gibbs free energy equation

Answer 2

DG =DH - TDS

Question 3

+ve entropy

Answer 3

difference from lows entropy (s) to higher entropy (l)

relative no. species increase as reaction goes left to right

Question 4

spontaneous reaction equation for G

Answer 4

DG = G(products) - G(reactant) < 0

Question 5

convenience of G spontaneous reaction

Answer 5

only need to calculate quantities for system and not surrounding

Question 6

law of mass action

Answer 6

concentration of R and P at any point in equilibrium reaction are related by reaction quotient (Q)

Question 7

in equilibrium equation

Answer 7

Q = kc

Question 8

Use of Q to predict direction of reaction

Answer 8

Q < kc - left to right

Q > kc - right to left

Question 9

kc

Answer 9

equilibrium constant

Question 10

kc equation and Q

Answer 10

[P]/[R]

must be e.g A / A(0)

Question 11

interpretation of equilibrium constant kc

Answer 11

R > P
R = P
R < P

Question 12

R > P

Answer 12

kc is a small number

Question 13

R = P

Answer 13

kc is some intermediate number

Question 14

R < P

Answer 14

kc is a big number

Question 15

connection between G and concentration

Answer 15

curve - positive curvature

Question 16

stage one of curve between G and conc

Answer 16

-ve gradient

DG - -ve spontaneous

Question 17

stage 2 of curve between G and conc

Answer 17

no gradient

equilibrium - DG = 0

Question 18

stage 3 of curve between G and conc

Answer 18

+ve gradient

DG - +ve therefore not occurring at A to B but spontaneous at B to A

Question 19

van’t Hoff isotherm

Answer 19

relationship of mass action ratio and G

derived yielding - vigourously

Question 20

equation for van’t Hoff isotherm

Answer 20

DG = DG* + RTln(Q)

Question 21

at equilibrium of van’t Hoff isotherm

Answer 21

DG* = - RTln(kc)

as DG = 0 and Q = kc

Question 22

predicting kc from DG*

Answer 22

kc = e(-DG*/RT) - exponential

Question 23

R

Answer 23

gas constant 8.13JK-1 mol-1

Question 24

DG*

Answer 24

in standard state