Week Nine Flashcards
negative delta G
spontaneous change will occur in forward
Dynamic equilibrium
a reaction that has no net change in overall composition
Kc equation
[A]^a [B]^b
Kc rule
only have one positive value at a particular temp
Qc
when not in equilibrium
can have any positive value
Kp
[PC/standard P]c [PD/standard P]d
—————————– [PA/standard P]a [PB/standard P]b
standard pressure
1 x 10^5 pa
Kp equation when given Kc
Kp = Kc(1000RT/standard pressure)^delta n gas
delta n gas equation
(number of moles of gaseous products) - (number of moles of gaseous reactants)
Changing the direction of equilibrium
the new equilibrium is the reciprocal of original
Kc’
reciprocal
1/Kc
Multiplying coefficient by a factor
the equilibrium constants are multiplied
Adding Chemical equilibriums
the equilbrium constants are multiplied
Kc3 = Kc1 x Kc2
Decreases in gibbs energy
spontaneous changes occur
Delta G of reaction equation
Delta G of reaction at standard + RTlnQ or RTlnK
where r is gas constant
t is temp
lnQ is log of reaction quotient
gas constant
8.314
large negative Delta G
equilibrium is towards products
large positive Delta G
equilibrium is towards reactants
Le chateliers Principle
equilibrium will try and counteract any changes and bring system back equilibrium
Adding or removing a product or reactant
alters concentration
Q changes and system is no longer at equilibrium
Changing volume of system
changes both concentration and partial pressure of reactant and product
Increasing volume
decreases partial pressure and total pressure
Qc equation
[nC]c [nD]d
—————- x V2
[nA]a[nB]b
Qc relationship with Volume
inproportional
Adding an inert gas at constant volume
increases total pressure but doesnt alter the position of equilibrium
Changing the temp of reaction mixture
equilibrium constant can be changed by altering the temp of a mixture
increasing temp - endothermic
increases k, products are favoured
increasing temp - exothermic
decreases k, reactants are favoured
Van Hoffs Equation
DlnK/Dt = delta H of reaction at standard/RT^2
Addition of catalyst
brings system to equilibrium more rapidly, position of equilibrium isnt affected
Change of gibbs free energy
(energy of higher phase) - (energy of lower phase)
Delta G >0
spontaneous change
Delta G = 0
no spontaneous change
delta of mix Gibbs free energy
always negative (due to increase in entropy)
Delta G at standard > 0
large amount of reactants
Delta G at standard < 0
large amount of products
QC
shift towards products
QC>Kc
shift towards reactants
Dln
change in K
Dt
change in temp
Equilibrium concentration
initial concentration + change in concentration
