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13 Cards in this Set

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lewis acids/bases
acid accepts electrons

base donates electrons

eg lewis acids have incomplete octet of electrons around central atom = AlCl3 BF3, simple cations EXCEPT alkali and heavier alkaline earth metal cations (Ca, Sr, Ba)

smaller the cation and higher charge, stronger the acid strength (Fe3+)
Bronsted and Lowry acids/bases
acid donates H+

Bases accept protons
molecular structure factors that determine whether a molecule containing a H will release its H into soln:
1 strength of bond holding H to molec

2. polarity of the bond

3. stability of the conjugate base

more Oxygens in oxyacids = stronger acid (share negative charge)
Hydrides
binary compounds containing H

can be basic, acidic or neutral

periodic table: basic to Left, acidic to the Right

also acidity increases going down table
acid dissociation constant
Ka= [H+][A-]/ [HA]

larger the Ka, the smaller the pKa and therefore stronger acid

Ka greater than 1 or pKa less than zero = strong
base dissociation constant
Kb= [OH-][HA]/ [A-]

(A-+H2O=OH-+HA)

larger the Kb, the smaller the pKb and therefore stronger base
Kw
10^-14 @ 25*C

Kw=KaKb
pKw= pKa + pKb
midpoint on titration curve straight line
equivalence point
stoichiometric point

for a monoprotic acid, point in titration where there are equal equivalents of acid and base in soln (same number MOLES not volume - bc concentrations can differ)

for equally strong acid base rxns, will be at pH 7 (NOT diprotic tho)
equivalence point of weak acid and strong base titration or vice versa
if base is stronger than acid, will be above 7

if acid stronger than base, will be below 7

half equivalence point = pKa
half equivalence point
where half of the acid has been neutralized by the base
= pKa

where could add largest amount of acid or base with least amt of change in pH
=BUFFERED!
Henderson-Hasselbalch eqn
pH=pKa+ log [A-] / [HA]
to make a buffer solution
start with acid with pKa closest to the pH we want to buffer our soln

mix equal amounts of that acid with its conjugate base

adding a small amt of water to an ideally dilute, buffered soln will have no effect on pH
indicators
usually a weak acid whose conjugate base is a different colour

point where indicator changes colour = endpoint
will only "equal" equivalence point if range covers the equivalence point