Page 29 - E-LKM ACID BASE

Lembar Kerja Mahasiswa - Asam Basa

Since CH COOH is a stronger proton donor than H O, in
3
2
CH COOH solvent, NH is more easily to accept proton. Therefore
3
3
the strength of NH increase in CH COOH solvent. Since
3
CH COOH is a stronger acid than H O or CH COOH is more acidic
3
2
3
than H O, the strength of NH , increases in a solvent which is
3
2
more acidic than water. In general, the strength of base
increases in acidic solvent.

D. The strength of hydrohalic acids

Hydrohalic acids are HF, HCI, HBr, and HI. All of them are
polar molecule with the halogen atom being electron rich and
the hydrogen atom being electron poor. The strength of these

acids depends on two things: polarity of H-X

The polarity of H-X bond increases with an increase in the

electronegativity of the halogen. The polarity of H-F bond>H-Cl
bond> H-Br bond> H bond. The polarity of H-X bond is related to

the ease of electron transfer from hydrogen atom to halogen
+
atom to give H and X. Based on the polarity

The strength of H-X bond affects the ease of the hydrohalic

acids to release H The weaker the H-X bond the easier the H to
be released and the stronger the hydrohalic acid. The strength

of covalent bond in H-F>H-Cl>H-Br>HI. HI is the easiest
hydrohalic acid to release H, while HF is the most difficult. Based

on the strength of H-X bond the acid strength of HF < HCI < HBr <
HI. Experimental results show that the strength of HF<HCI<HBr

<HI. This indicates that the effect of bond strength is greater
than the effect of bond polarity. HX (X=F, Cl, Br or I) is one of
many binary acids (acids consists of two elements). In general,

for binary acids of elements in the same group in the periodic
table, the bond strength is the more determinant factor than

the polarity of the bond in determining the acid strength.

(Effendy, 2011)

Bahasa Inggris Kimia (PKIM3139) 25