The knowledge of chemical analysis today has become important not only for scientists in their research but in fact bears influence in our daily routine as well. To recognize and classify these uses, we have to first understand, what is chemical analysis?Chemical AnalysisChemical Analysis is a body of procedures and techniques used to identify and quantify the chemical composition of a sample of substance.1 It may be said as a collection of all the techniques required to obtain any chemical information about a particular substance. There are two branches in analytical chemistry: Qualitative analysis and Quantitative analysis. Qualitative chemical analysis is used to identify a particular element/compound in a sample of substance. Quantitative chemical analysis consists of determining the quality or concentration of a specific sample of substance. Thus for example, determining whether a sample of salt contains the element chlorine is a qualitative analysis; measuring the percentage by weight of any chlorine in the sample is a quantitative analysis.
Qualitative AnalysisQualitative analysis is the determination of those elements and compounds that are present in a sample of unknown material. It is a method of analytical chemistry which seeks to find elemental composition of inorganic compounds. It is mainly focused on detecting ions in an aqueous solution, so that materials in other forms may need to be brought into this state before using standard methods. The solution is then treated with various reagents to test for reactions characteristic of certain ions, which may cause color change, solid forming and other obviously visible changes. A wet method qualitative analysis of inorganic ions proceeds by separating the ions into groups by selective precipitation reactions, isolating individual ions in the groups by an additional precipitation reaction, and confirming the identity of the ion by a reaction test that gives a specific precipitate or color. Several protocols exist for doing this, with cations (positively charged ions) and with anions (negatively charged ions).
Quantitative AnalysisQuantitative analysis is the determination of the amount by weight of each element or compound present in a particular sample of substance. The procedures by which this is achieved include testing for the chemical reaction of a presumed constituent with a reagent or for some well-defined physical property of the putative constituent. Classical methods include use of the analytical balance, gas manometer, burette, and visual inspection of color change. Gas and paper chromatography are important modern methods. Physical techniques such as use of the mass spectrometer and titration are also employed.
Titration:The most common way of doing quantitative analysis is by doing Titration. In this we can determine how much of a solution is needed to fully use up another solution and to complete the reaction. In titration, the atomic mass is used to calculate the number of moles of a substance required using the chemical formula. If we have the concentration of both the solutions then we can directly calculate the volume but in many cases, the concentration of one of the solutions is unknown. This is why one solution is titrated with another. Titration is usually done with an acid and alkali. The neutralization point (point of reaction completion) can determined using a pH indicator. At this point, the pH becomes 7 and the acid and alkali neutralize each other to become salt and water.
In titration, a known volume of one solution (Ex. Acid) is taken using a pipette and placed into a conical flask below the burette. Then a known volume of the other solution (Ex. Alkali) is poured into the burette. Then the valve is slowly opened and drop by drop, the alkali is decanted into the acid in the conical flask. Using the indicator as a guide, the neutralization point can be discerned at the point of colour change at pH 7. The volume of the alkali...
Bibliography: ook:Harwood, Richard (2004). IGCSE Chemistry. (Fourth Edition): Cambridge University Press.
Websites:http://en.wikipedia.org/wiki/Qualitative_Analysishttp://wulfenite.fandm.edu/labtech/qualanal.htmhttp://en.wikipedia.org/wiki/Titrationhttp://www.metrohm.com/applications/titration/potentiometric-titration.htmlEncyclopedia:Microsoft Encarta Encyclopedia 2004 Deluxe. Article: Chemical Analysis
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