Equilibrium-

• reactions can go in both directions:
  
• R --> P
• R <-- P
• when the rate of the forward reaction is equal to the rate of the reverse reaction (rate of R --> P = rate of R <-- P)
  
• no net change is observed
  

5 Flavas of K ~

1. K / Keq / Kc = standard K; concentrations are typically in molarities
2. Kp = for gasses; values used to calculate are partial pressures, not concentrations
3. Ksp = solubility product constant; uses molarities of slightly soluble compounds in aqueous solutions
4. Ka = weak acids (HAVEN'T LEARNED YET)
5. Kb = weak bases (HAVEN'T LEARNED YET)
   

Equilibrium constant = K

- For the general reaction a A + b B <--> c C + d D (italics are coefficients),

K = [C]^c[D]^d
[A]^a[B]^b also known as the equilibrium constant expression.

- If K>1, reaction is product-favored

- If K<1, reaction is reactant-favored

Equilibrium constant expression

- All concentrations at equilibrium values
- Product concentrations in numerator; reactant concentrations in denominator
- Concentration is raised to power of stoichiometric coefficient (from equation)
- K depends on reaction and temperature
- K has no units

- Concentrations of solid reactants/products are not included
- Concentration of (liquid) water is not included

Rules for Writing Kc Expressions:
-Kc is a function of temperature
-Do not put solids or pure liquids in the Kc expression
-Kc Reverse = 1/ Kc forward
-If you multiply the chemical equation by n, then you raise Kc to n
-If you add chemical reactions to get a final reaction, multiply the Kc's expression to get the final reaction Kc

Reaction Quotient = Q

- For the general reaction a A + b B <--> c C + d D (italics are coefficients),

Q = [C]^c[D]^d

[A]^a[B]^b

- At equilibrium, Q = K
- When Q<K, reactants --> products
- When Q>K, reactants <-- products

Dalton's Law of Partial Pressures

the total pressure of a gas system = the sum of the individual pressures

Pt = Pa + Pb + Pc . . .
Pt V = Nt RT
Kp = Kc * (RT) ^ delta N

R = universal gas constant, T = temperature, delta N = moles of gas product - moles of gas reactant

Ksp solubility product constant How much of a slightly soluble substance dissolves at a certain temperature
Solubility doesn't equal product constant

Solubility- How much of the solid or an ion is dissolved at a given temperature

- in the units of Molarity (mol/L) or g/L or g/mL

- Ksp cannot be compared directly unless they have EQUAL ion ratios

Solubility tells you how much of a solid can dissolved before the solution is saturated
-anything more than the solubility will precipitate out.
-any amount under solubility is unsaturated.
-supersaturated is a special case where the solution is holding more than it normally holds at that temperature. When it is disrupted, any amount over the solubilities will precipitate out.

Q< Ksp unsaturated (more will dissolve)
Q= Ksp saturated (no more will dissolve; any more will precipitate out)
Q> Ksp supersaturated(excess will precipitate out until Q=Ksp)

<-------------------------
COMMON ION EFFECT
AgI <--> Ag+ + I-
NaI

pH Rules
pH = -log[H+]
[H+] = 1 x 10^(-pH)
[H+][OH-] = 1 x 10^-14
pOH = - log [OH-]
pH + pOH = 14