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Analytical Chemistry

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Analytical chemistry is the science of obtaining, processing, and communicating information about the composition and structure of matter. In other words, it is the art and science of determining what matter is and how much of it exists.

The goals include a better understanding of the chemical structure of molecules, the ways in which different types of molecules interact, the morphology of solids and surfaces, and the nature of complex mixtures. Analytical Chemistry has applications in many fields, such as forensic science, life science, environmental science, and materials characterization.

Analytical chemistry can be divided into two major categories:
a) Qualitative Analytical Chemistry
b) Quantitative Analytical Chemistry.
Qualitative analysis consists of methods for establishing the qualitative chemical composition of a substance: that is, the identification of atoms, ions, and molecules that enter into the composition of the substance. Quantitative analysis consists of methods for determining the quantitative composition of materials: that is, the quantitative amounts of the chemical elements or of certain compounds. The purpose of a qualitative, quantitative, and characterization analysis is to solve a problem associated with a sample.

What is Analytical Chemistry?

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Analytical Chemistry is a branch of chemistry dealing with the qualitative and quantitative determination of chemical composition of materials. Analytical chemistry is often described as the area of chemistry responsible for characterizing the composition of matter, both qualitatively and quantitatively.

It deals with the identification of compounds and mixtures or the determination of the proportions of the constituents techniques commonly used is precipitation, spectroscopy, chromatography etc.

Analytical chemistry was defined as the chemical discipline that gains information on the chemical composition and structure of substances, particularly on the type of species, their amount possible temporal and spatial changes, and structural relationship between the constituents.
In other words "Analytical chemistry is found to be a scientific discipline that develops and applies methods, instruments and strategies to obtain information on the composition and nature of matter in space and time." 
Analytical Chemistry Hierarchy

Classical Methods

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In the early years of chemistry, most analyses were carried out by decomposing the samples and separating the components from the sample by ignition, fusion, precipitation or extraction. 

The sample or separated components were then treated with reagents that yielded products that could be recognized and thereby distinguished by color, boiling or melting point, solubility, odor, optical activity, refractive index or crystalline form.

The amount of analyte was quantitatively determined by gravimetric or by titrimetric methods which are now considered as classical methods: the calculations for classical analysis require no more information than experimentally measured weights, definite chemical reactions and atomic weights.

Instrumental Methods

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The field of instrumental methods is being continuously expanded. Different methods can be combined into "hybrid" or "hyphenated" and "multidimensional" methods. Methods can be divided according to the characteristic properties into methods based on the interaction of analyte with electromagnetic radiation such as absorption, fluorescence, phosphorescence, luminescence and chemiluminescence spectroscopy.

Fundamentals

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Analytical chemistry requires both basic and applied research with a view to develop new analytical tools or resources or to improve existing ones, in order to potentate basic element. The fundamental of analytical chemistry can propitiate developments in response to internal stimuli, which provide the strongest support for its existence as an independent entity. Analytical chemistry comprises the study of computing the chemical composition of resources, ways and means of data analysis that will be used throughout.


The placement of analytical chemistry is represented by the following picture:

Placement of Analytical Chemistry

Analytical Chemistry Experiments

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Method validation is the process of documenting or providing that an analytical method provides analytical data acceptable for the intended use.

The general procedure for establishing how an analysis will proceed is as follows:

Technique $\rightarrow$ Method $\rightarrow$ Procedure $\rightarrow$ Protocol

Some of the analytical chemistry experiments are given below:
1) Spectrophotometry
2) Chromotograpy
3) Calorimetry
4) Titrations
5) Gravimetry
6) Flame atomic absorption analysis
7) Quantitative analysis
8) Qualitative analysis
9) Infrared analysis

Analysis, Determination, and Measurement

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An analysis provides chemical or physical information about a sample. The components of interest in the sample are called analyte's, and the remainder of the sample is the matrix. In an analysis we determine the identity, concentration, or properties of the analyte's. To make this determination we measure one or more analyte’s chemical or physical properties.
Error is the difference between a single measurement or result and its true value. In other words, error is a measure of bias.

 Uncertainty expresses the range of possible values that a measurement or result might reasonably be expected to have.

Solved Examples

Question 1: Calculate the molarity of an acetic acid solution if 34.57mL of this solution are needed to neutralize 25.19mL of 0.1025M sodium hydroxide.
Solution:
CH3COOH(aq) + NaOH(aq) $\rightarrow$ Na+(aq) + CH3COO-(aq) + H2O(l)

M1V1 = M2V2

(M1)(0.03457) = (0.1025 moles)(0.02519)

M1 = 7.469 $\times$ 10-2M


Question 2: Calculate the pOH and the pH of a 5.0 $\times$ 10-2M solution of NaOH.
Solution:
[OH-] = 5.0 $\times$ 10-2M

pOH = -log (5.0 $\times$ 10-2) = 2 - log 5.0 

= 2 - 0.70 = 1.30

pH + 1.30 = 14.00

pH = 12.70


The Importance of Analytical Methodology

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Analytical Chemistry to this day is the oldest branch of Chemistry. Analytical approach is important when exploring the outcomes of environmental observation. In today’s era we cannot think of a single product which is of commercial purpose that has not been tested using analytical chemistry before utilization.

When designing and evaluating an analytical method, we usually make three separate considerations of experimental error. First, before beginning an analysis, errors associated with each measurement are evaluated to ensure that their cumulative effect will not limit the utility of the analysis. Errors known or believed to affect the result can then be minimized. Second, during the analysis the measurement process is monitored, ensuring that it remains under control. Finally, at the end of the analysis the quality of the measurements and the result are evaluated and compared with the original design criteria.