Page 12 - E-LKM Asam Basa_Neat

Formic acid, as shown in Figure 1.7,

is also a week acid. One hydrogen
atom that bonds to carbon atom in
this acid can be replaced with

electron donating substituent such
methyl group (CH ) to give acetic
3
acid.

Replacement of one non-acidic hydrogen atom of formic acid

with methyl group will increase electron cloud or electron density
of O-H bond. This will strengthen and shorten the H bond. Because

of this, the acidic hydrogen atom is more difficult to release and
the strength of acid decreases. Acitic acid is weaker than formic
acid.

Based on Brönsted-Lowry theory, base

such as ammonia (NH ) is a proton
3
acceptor. One of its hydrogen atoms can be
replaced with electron donating

substituents such as methyl group (CH ) to
3
give methylamine (CH NH ) shown in Figure
2
3
1.8.

Replacement of one hydrogen atom with
methyl group will increase availability of

electron cloud or electron density at the
nitrogen atom. This increases power of
nitrogen atom to attract proton.

Methylamine is stronger basic compare to
ammonia.

Replacement of three hydrogen atoms in the ammonia with

electron withdrawing substituents such as fluorine atoms will give
trifluoroammine. This replacement will decrease availability of

electron cloud or electron density at the nitrogen atom. This
decreases the power of nitrogen atom to attract proton.
Trifluoroammine is weaker basic compare to ammonia.

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