L7,8&9 - thermodynamics Flashcards
what happens to free energy during a spontaneous process
decreases
first law of thermodynamics
energy can neither be created or destroyed, but it can be transformed from one form to another.
what is the name of the region of interest of a reaction.
system
properties of isolated systems
no mass or heat transfer
second law of thermodynamics
for a process to occur spontaneously, the entropy of the thermodynamic universe must increase.
what is the Ka
-the equilibrium constant
-ratio of products to reactants
Gibbs free energy equation
ΔG = -RT ln Ka
G is the change of Gibbs free energy
R is the gas constant
T is the temperature
ΔG = ΔH - TΔS
H is enthalpy change
S is entropy change
what value of Gibbs is favourable vs unfavourable
if ΔG < 0 then favourable
if ΔG > 0 then unfavourable
what do you get when you take the natural log of a value less than 1
a negative number
ΔH effect on favourability
reactions with negative ΔH values are considered energetically favourable; they are more likely to occur
but some, reactions with positive ΔH values ( unfavourable) do occur.
units of entropy
J/mol/K
entropy equation (Boltzmann)
S = Kb ln N
kb is Boltzmann distribution
what is ΔG°’
(delta G nought prime)
the free energy change of a reaction taking place under standard conditions
25°C (298K)
pH 7 (for biological systems)
what is ΔG
the useful energy ‘available’ from a reaction
what is an exergonic reaction
ΔG < 0 reaction can occur spontaneously
