Chapter 2

Question 1

Favoured equilibrium and strenght of acid

Answer 1

Strong acid, products are favoured
weak acid, reactants are favoured

stronger acid (lower pKa) will be the acid

equilibrium favours formation of weaker acid (higher pKa)

Question 2

Acid strenght pKa

Answer 2

very strong: under 1
moderatly strong: 1-3
weak: 3-5
very weak: 5-15
useless: above 15

stronger acid, larger Ka, smaller pKa

Question 3

carboxylic acid

Answer 3

-COOH

double bond between O and C

pKa: 5 (weak acid)

Question 4

alcohols

Answer 4

-OH

as acidic as water

pKa: 15 (neutral)

Question 5

Amines

Answer 5

-NH2/3

basic

Question 6

protonated amines

Answer 6

-N(+)H3
slighlty acidic

positively charged

pKa: 10 (very weak)

Question 7

protonated carboxylic alcohols

Answer 7

more acidic

add proton/hydrogen on double bonded oxyge if available

pKa: less that 0 (as much as H3O+ protonated water) (strong acid)

Question 8

pKeq

Answer 8

HA + B = A- +HB+

pKeq= pKa (HA) - pKA (HB+)

Question 9

factors determining acid strenght

Answer 9

stability of its conjugate base
electronegativity
hybridization
size
substituents
delocalization

Question 10

stability of its conjugate base

Answer 10

the more stable a conjugate base is, the stronger the acid (when similar size, size matters more here)

H attached to more eletronegative atom makes the H more positive (e.atom attracts electrons) and will want to be released

FOCLNCH (most to least electronegative)

Question 11

electronegativity

Answer 11

acidity increases with electronegativity (from left to right))

Question 12

hybridization

Answer 12

higher the hybridization, weaker the acid because (sp more acid than sp3)

as s character increases, molecule gets stable with a formal charge, so will not want to be neutral

less red in drawing means more stable means less acidic

Question 13

size

Answer 13

acidicty increases with size (up to down)

H further away from atom so is easier detached (longer the bond weaker it is)

Question 14

substituents

Answer 14

more electronegative and closer the substituent is to the hydroxide group, more acidic

Inductive electron withdrawal (e.atom sucks electrons, which sucks electrons, etc, until at the hydroxide group

can also stabilize conjugate base by doing an inductive electron withdrawal towards most electronegative atom

Question 15

delocalization

Answer 15

more delecolization in an acid, more stable conjugate base, so stronger acid

Question 16

why is carbolyxic acids stronger than alcohol

Answer 16

1-inductive electron withdrawal from extra O causes H to be more positive and stabalizes conjugate base

2-delocalized electrons contribute to the extra stability to the conjugate base