Acids and Bases

Question 1

what is a bronsted acid

Answer 1

proton H+ donor

Question 2

what is a bronsted base

Answer 2

proton H+ acceptor

Question 3

what is a lewis acid

Answer 3

e- pair acceptor

electrophile

Question 4

what is a lewis base

Answer 4

e- pair donor

nucleophile

Question 5

large Ka

Answer 5

small pKa

stronger acid, rxn goes forward

Question 6

pKa formula

Answer 6

pKa = -logKa

Question 7

when pKa = pH

Answer 7

50% of acid has dissociated

Question 8

if pH > pKa

Answer 8

molecule is in deprotonated state

Question 9

if pH < pKa

Answer 9

molecule is in protonated state

Question 10

a strong acid will have a weak…

Answer 10

conj base

Question 11

a strong base will have a weak…

Answer 11

conj acid

Question 12

weak conj bases are…

Answer 12

more stable, less reactive

reverse rxn does not occur

Question 13

to determine conj base stability consider

Answer 13

Atom (EN + size)
Resonance
Induction
Orbital Hybridization

Question 14

“Atom” stability

Answer 14

acidity of HA goes up as you go –> row

acidity of HA goes up as you go down a group

Question 15

why EN?

Answer 15

more EN can hold a (-) charge

more EN has a greater dipole

easier to remove the H+

Question 16

why size?

Answer 16

(-) charge spread over a larger area

bond strength is lower as you go down a group

Question 17

“Resonance”

Answer 17

more resonance, (-) is delocalized and more stable

Question 18

“Inductive forces”

Answer 18

presence of additional EN atoms more stable

involves sigma bonds

Question 19

“Orbital Hybridization”

Answer 19

more stable sp (50% s char.) > sp2 (33% s char.) > sp3 (25% s char.) less stable

triple bonds > double bonds > single bonds

Question 20

why orbital hybridization?

Answer 20

more s-char, e- held more closely to nucleus, more stable

Question 21

strength of Lewis acid

Answer 21

stronger = better electrophile

1. molecules with unfilled octet
2. molecules w/ (+) charge AND resonance
3. molecules with partial (+) charge

Question 22

strength of Lewis base

Answer 22

stronger = better nucleophile

1. less EN attracts e- less
2. molecules w/ localized e-
3. molecules w/ (-) charge

Question 23

most stable base is the

Answer 23

least basic

Question 24

least stable base is the

Answer 24

most basic

Question 25

most acidic has

Answer 25

the most stable (weakest) base

Question 26

least acidic has

Answer 26

the least stable (strongest) base