L7-9 thermodynamics Flashcards
for a spontaneous process does free energy increase or decrease
decrease
what is the first law of thermodynamics
energy can not be created or destroyed
what is 2nd law of thermodynamics
for a process to occur spontaneously entropy must increase
define entropy
measure of dispersal of energy in a system
what does higher entropy mean
more disordered
is energy required to make a system less ordered or more ordered?
energy is required to produce order
what does a negative value of G mean
reaction feasible
what does a positive value of G mean
reaction not feasible
what does G=0 mean
reaction likely at equilibrium
does a negative or positive Ka indicate a feasible reaction?
positive
larger Ka = more favourable
what biological processes involve transfer of energy
photosynthesis protein folding mechanical work (muscles) synthesis of macromolecules ion gradients
what is coupling?
pairing an energetically unfavourable reaction with a favourable one (net energy favourable)
what is enthalpy
measure of energy within bonds
sum of energy required to break bonds and energy released from making bonds
why may average bond enthalpies not always be accurate
the are averages of the bond enthalpy in different compounds
eg HO-H will differ to CH3O - H
what does S>0 indicate
feasible reaction
explain entropy and the hydrophobic effect
using oil and water as example
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
how can enthalpy change be measured
calorimetry
effect of Hphobic surfaces on water
they decrease entropy of water by forcing water to form clathrate structures
what increases entropy
- solid —> liquid —> gas
- gas into bigger vol
- dilution of solution
- chem reaction that increases no. of molecules
- denaturing protein (one conformation - many)
what is Ka and Kd?
Ka –> forward equilibrium constant
Kd —> backwards equilibrium constant
define endergonic
energy change that increases free energy of the system
takes energy in from surroundings
define exergonic
energy change that decreases free energy of the system
releases energy into surroundings
is exergonic or endergonic favourable (spontaneous)
exergonic
does exergonic reaction have a +ve or -ve G value
negative
does endergonic reaction have a +ve or -ve G value
positive
does an endothermic reaction cause an increase or decrease in enthalpy
increase
does an exothermic reaction cause an increase or decrease in enthalpy
decrease
can a reaction be exergonic and endothermic?
yes
a reaction can be favourable even if its enthalpy is unfavourable
