L7-9 thermodynamics

Question 1

for a spontaneous process does free energy increase or decrease

Answer 1

decrease

Question 2

what is the first law of thermodynamics

Answer 2

energy can not be created or destroyed

Question 3

what is 2nd law of thermodynamics

Answer 3

for a process to occur spontaneously entropy must increase

Question 4

define entropy

Answer 4

measure of dispersal of energy in a system

Question 5

what does higher entropy mean

Answer 5

more disordered

Question 6

is energy required to make a system less ordered or more ordered?

Answer 6

energy is required to produce order

Question 7

what does a negative value of G mean

Answer 7

reaction feasible

Question 8

what does a positive value of G mean

Answer 8

reaction not feasible

Question 9

what does G=0 mean

Answer 9

reaction likely at equilibrium

Question 10

does a negative or positive Ka indicate a feasible reaction?

Answer 10

positive

larger Ka = more favourable

Question 11

what biological processes involve transfer of energy

Answer 11

photosynthesis 
protein folding 
mechanical work (muscles) 
synthesis of macromolecules 
ion gradients

Question 12

what is coupling?

Answer 12

pairing an energetically unfavourable reaction with a favourable one (net energy favourable)

Question 13

what is enthalpy

Answer 13

measure of energy within bonds

sum of energy required to break bonds and energy released from making bonds

Question 14

why may average bond enthalpies not always be accurate

Answer 14

the are averages of the bond enthalpy in different compounds
eg HO-H will differ to CH3O - H

Question 15

what does S>0 indicate

Answer 15

feasible reaction

Question 16

explain entropy and the hydrophobic effect

using oil and water as example

Answer 16

if oil and water were to mix water would have to surround every oil molecule decreasing the number of states it could be in and therefore decreasing entropy

reducing exposed Hphobic SA by creating 2 layers means less h2o has to exist in unfavourable state

Question 17

how can enthalpy change be measured

Answer 17

calorimetry

Question 18

effect of Hphobic surfaces on water

Answer 18

they decrease entropy of water by forcing water to form clathrate structures

Question 19

what increases entropy

Answer 19

1. solid —> liquid —> gas
2. gas into bigger vol
3. dilution of solution
4. chem reaction that increases no. of molecules
5. denaturing protein (one conformation - many)

Question 20

what is Ka and Kd?

Answer 20

Ka –> forward equilibrium constant

Kd —> backwards equilibrium constant

Question 21

define endergonic

Answer 21

energy change that increases free energy of the system

takes energy in from surroundings

Question 22

define exergonic

Answer 22

energy change that decreases free energy of the system

releases energy into surroundings

Question 23

is exergonic or endergonic favourable (spontaneous)

Answer 23

exergonic

Question 24

does exergonic reaction have a +ve or -ve G value

Answer 24

negative

Question 25

does endergonic reaction have a +ve or -ve G value

Answer 25

positive

Question 26

does an endothermic reaction cause an increase or decrease in enthalpy

Answer 26

increase

Question 27

does an exothermic reaction cause an increase or decrease in enthalpy

Answer 27

decrease

Question 28

can a reaction be exergonic and endothermic?

Answer 28

yes

a reaction can be favourable even if its enthalpy is unfavourable