Page 19 - E-LKM ACID BASE_Neat

Lembar Kerja Mahasiswa - Asam Basa

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 Figure 11. FormicAcid
3
acid. nb: silhakan klik gambar
untuk memperbesar gambar
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
3
2
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. Figure 12.
Methylamine is stronger basic compare to Ammonia (top) and
methylamine

ammonia. (bottom)
Replacement of three hydrogen atoms in nb: silhakan klik
gambar untuk
the ammonia with electron withdrawing memperbesar gambar

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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