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1 Analytical Chemistry

الكلية كلية العلوم للبنات     القسم قسم الكيمياء     المرحلة 1
أستاذ المادة محمد حامد سعيد الدهيمي       15/12/2012 18:08:11
Analytical Chemistry
1st Class 1st Semester 2012/2013
Reference text:-
1- Fundamentals of Analytical Chemistry by Stook and West
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Lecture No. 1 Date : 1/12 /2012
Dr. Mohammed Hamed

Historic acid–base theories
Lavoisier s oxygen theory of acids
The first scientific concept of acids and bases was provided by Lavoisier circa 1776. Since Lavoisier s knowledge of strong acids was mainly restricted to oxoacids, such as HNO3 (nitric acid) and H2SO4 (sulphuric acid), which tend to contain central atoms in high oxidation states surrounded by oxygen.
The Lavoisier definition was held as absolute truth for over 30 years, until the 1810 article and subsequent lectures by Sir Humphry Davy in which he proved the lack of oxygen in H2S, H2Te, and the hydrohalic acids. However, Davy failed to develop a new theory, concluding that "acidity does not depend upon any particular elementary substance, but upon peculiar arrangement of various substances". One notable modification of oxygen theory was provided by Berzelius, who stated that acids are oxides of nonmetals while bases are oxides of metals.
Liebig s hydrogen theory of acids
This definition was proposed by Justus von Liebig circa 1838, based on his extensive works on the chemical composition of organic acids. This finished the doctrinal shift from oxygen-based acids to hydrogen-based acids, started by Davy. According to Liebig, an acid is a hydrogen-containing substance in which the hydrogen could be replaced by a metal.
In 1884 Svante Arrhenius suggested that salts such as NaCl dissociate when they dissolve in water to give particles he called ions.
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