Acid-Base Equilibrium and Titration Concepts

Auto-ionization of water

Water dissociates into H+ and OH- ions.

Kw

Ion product constant for water at 25°C.

Kw value

1.0 x 10^-14 at 25°C.

pH

Negative logarithm of hydrogen ion concentration.

pOH

Negative logarithm of hydroxide ion concentration.

Strong acids

Completely dissociate in solution.

Strong bases

Completely dissociate in solution.

Weak acids

Partially dissociate in solution.

Weak bases

Partially dissociate in solution.

Ka

Acid dissociation constant.

Kb

Base dissociation constant.

Percent dissociation

Measure of ionization in weak acids/bases.

Henderson-Hasselbalch equation

pH = pKa + log([A-]/[HA]).

ICE table

Used to calculate concentrations at equilibrium.

Equivalence point

Point where moles of acid equals moles of base.

Titration

Process of adding a solution to determine concentration.

Net ionic equation

Simplified equation showing only ions involved.

Conjugate base

Species formed when an acid donates a proton.

Conjugate acid

Species formed when a base accepts a proton.

Buffer solution

Resists changes in pH upon addition of acids/bases.

Blood buffer system

Maintains blood pH using bicarbonate and carbonic acid.

pH of strong acid

Calculated as -log[strong acid concentration].

pH of strong base

Calculated as -log[strong base concentration].

Weak acid pH calculation

Use ICE table and Ka for weak acids.

Weak base pH calculation

Use ICE table and Kb for weak bases.

pH of weak acid at equivalence

Determined by concentration of conjugate base.

pH of weak base at equivalence

Determined by concentration of conjugate acid.

pH of strong acid and strong base titration

Always equals 7 at equivalence point.

pH of weak acid and strong base titration

Greater than 7 at equivalence point.

pH of strong acid and weak base titration

Less than 7 at equivalence point.

pH calculation from concentration

pH = -log[H+].

pOH calculation from concentration

pOH = -log[OH-].

Ionization of HF

HF dissociates into H3O+ and F- in water.

Stoichiometry in titration

Used to calculate amounts of reactants.

Limiting reactant

Reactant that is completely consumed in reaction.

Total volume in titration

Sum of volumes of acid and base solutions.

pH calculation after titration

Use concentrations of remaining species.

pH at half equivalence point

pH equals pKa for weak acids.

pH of buffer solution

Calculated using concentrations of acid and conjugate base.

pH after equivalence point

Determined by excess hydroxide ions.

Weak acid dissociation

Weak acids have Ka values much less than 1.

Strong acid examples

HCl, HNO3, H2SO4.

Strong base examples

NaOH, KOH, LiOH.

Weak acid examples

HF, CH3COOH.

Weak base examples

NH3, CH3NH2.

pH of buffer with salt

Use Henderson-Hasselbalch with salt concentration.

pKa

Negative logarithm of Ka.

pKb

Negative logarithm of Kb.

pH of solution after adding salt

Depends on concentrations of acid and conjugate base.

Equilibrium expression for water

Kw = [H+][OH-].

pH of 3.00 M HF

Calculated as 1.33 from given Ka.

Percent ionization formula

% ionization = ([H+]/[HA]) x 100.