Chemical Equilibrium 10

What signals a reversible reaction

double arrows

Dynamic Equilibrium

the rate of forward and reverse reactions are equal and still moving

Equilibrium constnat equaition

C^c D^ d / A^a B^b from reaction aA + bB = c C + dD

IMPORTANT FOR EQUILIBRIUM ABOUT CONC

only looks at (aq) and (g) not (s) or (l)

Kc equation

C^c D^d/ A^a B^b

Kp equation

Pc^c PD^d / PA^a PB^b

if K eq < 1

There is greater concentration of reactant than products at equilibrium

if Keq = 1

The equilibrium is equalI

If Keq > 1

There is greater concentration of products than reactants at equilibrium

If products are lower in energy than reactatns

more stable and exergonic and spontaneous

if products are higher in energy than reactants

less stable and endergonic and non sponatneous

Keq to Gibbs formula

DeltaG = -RTln(Keq)

If Keq < 1 and ln(Keq) < 0

delta g postive and reactants favored

If Keq > 1 and ln(Keq) > 0

delta g is negative and products are favored

If Keq = 1 and ln(Keq) = 0

delta g is zero and ratio of reactants and products are equal

Reaction Quotient

uses concetnration of the reactants and products at any point in the reaction

Reaction Quotient Equation

Q = Cc Dd/Aa Bb

If Q < K

high concentration of reactants than there is at equilibrium and reactions proceed forward and shift right

If Q = K

the reaction is at dynamic equilibrium

If Q > K

there is higher conc of products and the reactions proceeds in reverse and shift left

If Reactants are added

Q < K eq so reactions shift towards the forward reaction i

if reactants are removed

Q > Keq and the reactiions shifts to the left toward the reactants

If products are added

Q > Keq shift toward the reverase reaction

if products are removed

Q < Keq reactions shift toward forward reaction

In reagrasd to change in pressure of compression where volune decreases and pressure increases

the reaction shifts toward the side with fewer moles of gas

If the pressure decreases and volume increases

the reaction shifts toward the side of more moles of gas

Change of concentration iwth endothermic reaction

endothermic reaction have heat as reactant

lower temp menas shift to left

higher temp means shift to right

Change of conc with exothermic reaction

heat would be a product

lower temp shifts toward right

hgiher temp shift towards left

Precipitate

Ions in solution that create a solid

Ksp Or Solubility product constant

Solids and liquids are not included only aq w

what is the ksp of PbI2 (s) = PB2+ (aq) + 2I- (aq)

ksp = Pb²+] [I^- )²

Solubility Product Quotient or Qsp

Qsp = the same as Ksp

If Qsp < Ksp

then the solution can still dissolve more solute to reach equilibrium and proceed in forward reaction and create more ions

Unsaturated means

Qsp < Ksp

can dissolve more solute

Saturated

Qsp = Ksp

cannot dissolve more

Supersaturated

Qsp > Ksp

Formation of precipitate

Molar Solubility

number of moles that can dissolved per liter of solution until soltion becomes satured

Common Ion Effect

Decrease in solubility of an ionic precipiate if then there would be lower solubility and more precipiate

if we put AgCl in a salt water what would happen

due to common ion effect there would be more precipate due to similar ions

Acid

Donates H

Base

Accepts H

Amphoteric Species

Act as an Acid or a base

Autoionization of Water

proton transferred from one water molecule to another water moecule

Kw

Kw = 1.0 × 10^-14

Ka

Ka = (Conjugate acid)(conjugate base)/ Acid

pKa

-log (Ka)

Kb

Kb = Conjugate base (Conjugate Acid)/ Base

Pkb

-log (kb)

Kw in terms of ka and kb

Kw = KA * KB

pka + pkb =

14

The Kw will change at different temperatures

know this