Chateliers Le Principle
Disturbances: concentration, pressure, and
temperature
Shift in eqm RXN
Shift in eqm RXN
Change in Concentration
-System reacts in the direction that reduces the
change
- eqm shifts when on left
- eqm shifts when on right
- disturbance is reduced but not eliminated, position
of eqm shifts
Change in Pressure/Volume
- adding inert gas has no effect
- change in V = change in [C]
- change in P b/c of V does not change Kc
- if V P RXN shifts so that total no. of gas
,
molecules &(vice versa)
-if ngas=0, no effect on eqm positin
Change in Temperature
- T will K for system w/ Hrxn >0
- T will K for system w/ Hrxn<0
Fp depression: Tf = imKf
Osmotic Pressure: = iMRT
Exothermic heats w/H2O: (SO32-, SO2-4, SeO42-,
AsO4-, PO42-) solubility in H2O as T and S >0
K = [Products]eq/[Reactants]eq
Q= [Products]/[Reactants]
Q<K Reactants
@ products
Q>K Eqm G = 0, G = -RTlnK
K = exp(- G/RT)
G < 0 right
G > 0 left
If G > 0 spontaneous backwards
K > 1 : more products
K < 1 : more reactants
G = G + RTlnQ
K vs T: exo H <0, T, K reactant
,
K vs T: endo H >0, T, K product
,
A+heat B endo T K
A B +heat exo T K
K = exp(- H/RT - S/R)
Ion pair formation: lower i,: VP BP
FP
CH4 (g) CH4(aq) : K is greater @ lower T
Acids and Bases
HA + H2O <--> H3O+ + AKa = [H3O+][A-] / [HA]
pKa = -logKa
A- + H2O <--> HA + OHKb= [HA][OH-] / [A-]
pKb= -logKb
Ka x Kb = Kw -- Kw = 1 x 10-14
Ionization
weak acid: [c] %I [H3O+] pH
,
,
,
weak base:: [c] , [OH-] pH
,%I
,
strong acid/base: 100% ionization
Acidity icreases with charge
Acidity with smaller radius
R = 8.3145 J/K-mol
Daltons Law of Partial Pressure: Ptot=Pa+Pb
Higher B.O shorter Bond stronger