Ch 6 Acid Base Equilibrium

Question 1

strong vs weak electrolytes

Answer 1

strong:
- alkali and alkaline earth hydroxides
- most salts

weak:
- organic acids
- ammonia + most organic bases
- halides, cyanides, thiocyanates of Hg, Zn, Cd

Question 2

autoprotolysis

Answer 2

Amphiprotic solvents undergo self-ionization to form a pair of ionic species
ex. water splitting into hydroxide + hydronium

Question 3

chemical equilibrium

Answer 3

ratio of product:reactant is equal
rate of forward + backward is the same

Question 4

mass action effect

Answer 4

shift in equilibrium brought about by changing the amount of one of the participating species

Question 5

solubility product constant

Answer 5

Ksp = [ion][ion]
solid keeps dissolving until the concentration of ions equals solubility constant

Question 6

charge balance vs mass balance equations

Answer 6

charge:
coefficients = charge value

mass:
a[bA] = b[aB]
C(total) = [HA] + [A-]

Question 7

how to check assumption that cHA - [H3O+] ~ cHA formula

Answer 7

cHA / Ka >= 10^3

Question 8

henderson hasselbalch formula

Answer 8

pH = pKa + log(cA-/cHA)

Question 9

buffer capacity formula + defn

Answer 9

ß = ∆cb / dpH = -∆ca / dpH
Number of moles of strong acid or strong base that 1L of the buffer can absorb without changing the pH by more than 1

Question 10

ability of a buffer to prevent a significant change in pH is related to

Answer 10

1. total conc of buffering species
2. total conc. ratio of buffering species

Question 11

choosing acid based on buffer

Answer 11

acid with pKa within ± desired pH