pKa values

[image][image]

20
HI
-10
HCl
-7
H2SO4
ca. -3
HSO4
2.0
[image]
4.8
H2S
7.0
NH4+
9.2
[image]
10.0
phenol
10
acetone
20.0
methanol

15.5

 

CH3OH
15.5
[image]
25
alkyne
25
NH3
33
ammonia
33
C6H6
ca. 43
benzene
43
CH4
ca. 48
 methane
ca. 48
ethyne
25
will ammonia deprotonate ethylene?

yup. ammonia pKa 33, ethylene pKa 25

it’s the amide ions that will deprotonate the ethylene, not ammonia itself

pKas of:

ethane,

ethene,

ethylene

50,

44,

26

;

[image] ,; [image],;[image]

;

15.9, 4.8, -1.9

The trend is due to the fact that the respective conjugate bases get more stable for compounds left to right bc of nr of O atoms. pretty cool

why does ethane has higher pKa than ethene?
Upon the removal of H from ethane, the e will stay in an sp3 orbital, which is less stable than an sp2 orbital resulting from deprotonation of ethene.
Are e in sp or sp2 orbitals lower in energy?
sp, because an sp orbital has more s character than an sp2 orbital. An s orbital is more stable bc s orbitals are closer to the nucleus and very low in energy
x

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