pKa values

alkane

50

-single bonds

alkene

45

-double bonds

amine

40

H-N- 2 R groups

hydrogen

35

H-H bonding

alkyne

25

-triple bond

alcohol

17-18

H-O- R group (not another hydrogen)

water

16

H-O-H

bicarbonate ion

11

H- CO3 (double bond to 1 O and single bond to 2 O)

ammonium ion

10

+ charge on nitrogen -H and 3 R group bonding

carbonic acid

6

H2- CO3 (double bond to 1 O and single bond to 2 O)

(add another H bonded to O to make it carbonic not bicarbonic)

carboxylic acid

5

H-CO2 with another R group attached to C

oxonium ions

(strong acid) -2
-1 hydrogen attached, 2 R groups

(strong acid) -3

-3 hydrogen attached, 0 R groups

HBr

-5

HCl

-5

HI

-5

H2SO4

-5

TsOH

-5

HNO3

-5

HClO4

-5

Postive pKeq value

favors the reverse reaction

Negative pKeq value

favors the forward reaction

Postive Keq exponent

favors the forward reaction

Negative Keq exponent

favors the reverse reaction

pKb value

the lower the pKb value= the stronger base = reaction favored

At equilibrium, if more mols of base (A-) are present…

the pH is higher than the given pKa value

(bases raise the pH)

At equilibrium, if more mols of acid (HA) are present…

the pH is lower than the give pKa value

(acids lower the pH)