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تاريخ التسجيل : 22/03/2009
|موضوع: Fundamental of Analytical Chemistry الأربعاء مارس 10, 2010 3:19 pm|| |
What is Analytical Chemistry ?
The First lecture covers the following points:-
- What is Analytical Chemistry
- Classification of Analytical Methods
- Plane of Analysis
Analytical chemistry is a measurement science consisting of a set of
powerful ideas and methods that are useful in all fields of science and
medicine. Qualitative analysis establishes the chemical identity of the
species in the sample. Quantitative analysis determines the relative
amounts of these species or analytes in numerical terms.
Analytical chemistry plays a vital role in the development of science.
The concentration of oxygen and of carbon dioxide are determined in
millions of blood samples every day and use to diagnose and treat
illnesses. Quantities of hydrocarbons, nitrogen oxides and carbon
monoxide present in automobile exhaust gases are measured to determine
the effectiveness of smog control devices. Quantitative measurements of
ionized calcium in blood serum help diagnose parathyroid disease in
Quantitative analytical measurements also play a
vital role in many research areas in chemistry, biochemistry, biology,
geology, physics and the other sciences.
Classifying Quantitative Analytical Methods
We compute the results of a typical quantitative analysis from two
measurements. One is the mass or the volume of sample to be analyzed.
The second is the measurement of some quantity that is proportional to
the amount of analyte in the sample, such as mass, volume, intensity of
light or electrical change.
We classified quantitative methods into:
1- Volumetric Methods
2- Gravimetric Methods
3- Electro analytical Methods
4- Spectroscopic Methods
5- Miscellaneous Methods
Plane of Analysis
Atypical quantitative analysis involves the sequence of steps
1- Defining the problem.
At first present a case study to illustrate steps in solving an important and practical analysis problem
The next step in a quantitative analysis is to acquire the sample. To
produce meaningful information, an analysis must be performed on a
sample whose composition faithfully represents that of the bulk of
material from which it was taken. Where the bulk is large and
heterogeneous, great effort is required to get representative sample.
- 3- Processing the sample
The third step in an analysis is to process the sample in any of a
variety of different ways. The first step in processing the sample is
often the preparation of a laboratory sample.
a-Drying the sample.
b-Dissolving the sample.
c-Performing the required separations.
4-Making the appropriate measurements.
All analytical results depend on a final measurement of a physical or
chemical property of the analyte. This property must vary in a known
and reproducible way with the concentration of the analyte.
5-Making data presentation.
Analytical results are incomplete without an estimate of their
reliability. The experimenter must provide some measure of the
uncertainties associated with computed results if the data are to have