Acids and Bases Flashcards
what is a bronsted acid
proton H+ donor
what is a bronsted base
proton H+ acceptor
what is a lewis acid
e- pair acceptor
electrophile
what is a lewis base
e- pair donor
nucleophile
large Ka
small pKa
stronger acid, rxn goes forward
pKa formula
pKa = -logKa
when pKa = pH
50% of acid has dissociated
if pH > pKa
molecule is in deprotonated state
if pH < pKa
molecule is in protonated state
a strong acid will have a weak…
conj base
a strong base will have a weak…
conj acid
weak conj bases are…
more stable, less reactive
reverse rxn does not occur
to determine conj base stability consider
Atom (EN + size)
Resonance
Induction
Orbital Hybridization
“Atom” stability
acidity of HA goes up as you go –> row
acidity of HA goes up as you go down a group
why EN?
more EN can hold a (-) charge
more EN has a greater dipole
easier to remove the H+
why size?
(-) charge spread over a larger area
bond strength is lower as you go down a group
“Resonance”
more resonance, (-) is delocalized and more stable
“Inductive forces”
presence of additional EN atoms more stable
involves sigma bonds
“Orbital Hybridization”
more stable sp (50% s char.) > sp2 (33% s char.) > sp3 (25% s char.) less stable
triple bonds > double bonds > single bonds
why orbital hybridization?
more s-char, e- held more closely to nucleus, more stable
strength of Lewis acid
stronger = better electrophile
- molecules with unfilled octet
- molecules w/ (+) charge AND resonance
- molecules with partial (+) charge
strength of Lewis base
stronger = better nucleophile
- less EN attracts e- less
- molecules w/ localized e-
- molecules w/ (-) charge
most stable base is the
least basic
least stable base is the
most basic
