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
most acidic has
the most stable (weakest) base
least acidic has
the least stable (strongest) base
