Sunday 10 April 2011

qualitatve n quantitve

Quantitative vs. Qualitative


quantitative techniques to determine the amount of each compound in the sample. Careful procedures for recognizing the presence of different metal ions have been developed, although they have largely been replaced by modern instruments; these are collectively known as qualitative inorganic analysis. Similar tests for identifying organic compounds (by testing for different functional groups) are also known.
Many techniques can be used for either qualitative or quantitative measurements. For instance, suppose an indicator solution changes color in the presence of a metal ion. It could be used as a qualitative test: does the indicator solution change color when a drop of sample is added? It could also be used as a quantitative test, by studying the colour of the indicator solution with different concentrations of the metal ion. (This would probably be done using ultraviolet-visible spectroscopy.)
quantitative analysis is the determination of the absolute or relative abundance (often expressed as a concentration) of one, several or all particular substance(s) present in a sample.
Once the presence of certain substance(s) in a sample is known, the study of their absolute or relative abundance can help in determining specific properties. Knowing the composition of a sample is very important and several ways have been developed to make it possible, like gravimetric and volumetric analysis. Gravimetric analysis yields more accurate data about the composition of a sample than volumetric analysis does, but the first one takes more time to perform in the laboratory. Volumetric analysis in the other side doesn't take that much time and the results that we obtain are in the most cases satisfactory. Volumetric analysis can be simply a titration based in a neutralization reaction but it can also be a precipitation or a complexn forming reaction as well as a titration based in an redox reaction. However, each method in quantitative analysis has a general specification, in neutralization reactions, for example, the reaction that occurs is between an acid and a base, which yields a salt and water, hence the name neutralization. In the precipitation reactions the standard solution is in the most cases silver nitrate which is used as a reagent to react with the ions present in the sample and to form a high insoluble precipitate. Precipitation methods are often called simply as Argentometry. In the two other methods the situation is the same. Complex forming titration is a reaction that occurs between metal ions and a standard solution that is in the most cases EDTA (ethylene diamine tetra acetic acid). In the redox titration that reaction is carried out between an oxidizing agent and a reduction agent.

5 comments:

  1. hi to all my frdns..this is istgsh btween qlttve n quanttve..u cn learn from my blog

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  2. wow...i can learn this here...i no need to find in the big book..hehe

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  3. Hehehe thank you yunie, now i have this important information....

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  4. i don't know that you love chemistry this much...

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