Quantitative analysis gravimetric

Qualitative and quantitative analysis (gravimetric, titrametric and instrumental techniques)... 

In some situations the rate at which a precipitate forms can be used to separate an analyte from a potential interferent. For example, due to similarities in their chemistry, a gravimetric analysis for Ca + may be adversely affected by the presence of Mg +. Precipitates of Ca(01T)2, however, form more rapidly than precipitates of Mg(01T)2. If Ca(01T)2 is filtered before Mg(01T)2 begins to precipitate, then a quantitative analysis for Ca + is feasible. 

Harris, T. M. Revitalizing the Gravimetric Determination in Quantitative Analysis Laboratory, /. Chem. Educ. 1995, 72, 355-356. 

The quantitative analysis procedure involves gravimetric detn of the HMX on a moisture-free basis after benzene extraction of, and differential detn of TNT. Moisture content is detd by conductometric titration of sample in an acetic-sulfuric acid suspension. Acetone insoluble matter is determined gravimetrically... 

Precipitation reactions have many applications. One is to make compounds. The strategy is to choose starting solutions that form a precipitate of the desired insoluble compound when they are mixed. Then we can separate the insoluble compound from the reaction mixture by filtration. Another application is in chemical analysis. In qualitative analysis—the determination of the substances present in a sample—the formation of a precipitate is used to confirm the identity of certain ions. In quantitative analysis, the aim is to determine the amount of each substance or element present. In particular, in gravimetric analysis, the amount of substance present is determined by measurements of mass. In this application, an insoluble compound is precipitated, the precipitate is filtered off and weighed, and from its mass the amount of a substance in one of the original solutions is calculated (Fig. 1.6). Gravimetric analysis can be used in environmental monitoring to find out how much of a heavy metal ion, such as lead or mercury, is in a sample of water. 

Two methods commonly used in quantitative analysis are gravimetric and volumetric analyses. 

GRAVIMETRIC ANALYSIS. A type of quantitative analysis involving precipitation of a compound that can be weighed and analyzed after drying. It is also used in determining specific gravity. 

Mizukami, S., and T. Ichi Organic Quantitative Analysis on the Microgram Scale. I. Gravimetric Determination of Metals in Water and in Organic Compounds. Microchim. Acta 1966, 147. 

As a matter of economy, in both time and paper, titles should be short. However, the title "Chemistry alone might refer merely to a definition of the word or it could be the title of a multivolume treatise covering all of the known chemical elements and their compounds. As a book title, "Quantitative Analysis may apply to anything from a very short book, perhaps with simple gravimetric and titrimetric laboratory exercises, to a treatise sufficiently comprehensive to require a score of volumes to cover all kinds of methods applied to all kinds of materials ... 

A At Harvard 1 took a course on quantitative analysis for which we had to do the gravimetric analysis of calcium in limestone. But the instructor told us that we were wasting our time any sensible person would use atomic spectroscopy. I asked what it was and he told me to read a small book written by Gerhard Herzberg, who would later win a Nobel Prize for spectroscopy. 1 did, and that summer at home I made my own carbon arc for taking atomic spectra of various compounds. 

Analytical methods can be classified in many different ways. Often we distinguish a method of identifying chemical species, a qualitative analysis, from one that deteiTnines the amount of a constituent, a quantitative analysis. Quantitative methods, as discussed in Section IB, are traditionally classified as gravimetric. 

For an exact characterization of the investigated systems, besides the isotope ratio measurement, one has to carry out the quantitative analysis of polyethers, and of the corresponding metal complexes as well. The analysis method which is most commonly described in the literature for polyethers is NMR spectrometry However, this spectroscopic method is not very precise for a quantitative determination. Therefore, other types of analysis have been developed, e.g. a gravimetric procedure and a titrimetric method using the standard addition technique with a potentiometric indication... 

In a chemical analysis, especially involving quantitative analysis, the amount of chemical used is critical and can be determined by the measurement of concentration if it is a solution, or by weight, if it is a solid. Sometimes, the concentration of a solution can be easily determined by using another known solution through titration. For acids and bases, if the concentration is sufficiently low, the pH concept is generally used to represent the concentration of the acid or base in the aqueous solution. For the analysis of common chemicals, such as caustic soda, acetic acid, soda ash, sodium dithionite, hydrogen peroxide, and so on, titrimetric analysis and gravimetric analysis are widely used. For the analysis of surfactants and other chemicals, qualitative spot tests and specialised instruments should be utilised. 

Quantitative determination is usually made gravimetrically, after extraction with dichloromethane or dioxane, whereby a separate extraction with petroleum ether is made to determine the quantity of extractable spinning oils. In this way the maximum fraction of extractable oligomers is determined, not the total oligomer content. The marked UV absorption at 250 nm also enables quantitative determination. More details of quantitative analysis can be found in the literature - - and further information, also on repairing faulty pieces, is available. ... 

As IR spectroscopy is a secondary method of analysis, the development of quantitative analysis methods requires calibration with a set of standards of known composition, prepared gravimetrically or analysed by a primary chemical method, to establish the relationship between IR band intensities and the compositional variable(s) of interest. Once a calibration has been developed, it can then be used for the prediction of unknowns, provided two general conditions are met i) the spectra of the unknowns are recorded under the same conditions as employed in the calibration step (i.e., same instrumental parameters, identical means of sample handling, etc.) and ii) the composition of the calibration standards is representative of that of the unknowns. 

The most common method for the quantitative analysis of total fats in foods has been gravimetric, where the components of the sample are extracted into a suitable solvent (e.g., methylene chloride), the solvent is then removed by evaporation, and the residue is weighed. When using such a classic traditional technique, the final liquid extraction volume (hquid organic solvent) required may exceed 100 mL. 

Now that we have discussed the concentration and dilution of solutions, we can examine the quantitative aspects of reactions in aqueous solution, or solution stoichiometry. Sections 4.6. 8 focus on two techniques for studying solution stoichiometry gravimetric analysis and titration. These techniques are important tools of quantitative analysis, which is the determination of the amount or concentration of a substance in a sample. 

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