Silver qualitative analysis

In similar circumstances, silver salts leave a residue of metallic silver lead and copper salts usually leave a residue of the corresponding oxide calcium and barium salts leave a resirlne of the carbonate or oxide. Identify the metal in all such cases by the usual tests of qualitative inorganic analysis. Metals other than the above are seldom encountered in elementan qualitative analysis. 

Students usually identify the existence of anions such as carbonate, iodide and sul-fate(VI) by adding a barium/silver(I)/lead(II) solution to the unknown, followed by a dilute acid or vice-versa in qualitative analysis practical work sessions and examinations. Mat r students had difficulty understanding the roles of the bar-ium/silver(I)/lead(II) solution and the dilute acid in the tests for anions. For example, 20% believed that the addition of aqueous barium nitrate(V) followed by dilute nitric(V) acid was to test for sulfate(VI) only. Another 25% believed that to test for a carbonate, acid had to be added directly to the unknown sample, while 20% believed that the addition of barium nitrate(V) invalidated the test for carbonates. When the students were asked the purpose of adding dilute nitric(V) acid following die addition of silver nitrate(V) solution (in one question) and lead(II) nitrate(V in another question) to the unknown solutions, 22% and 35%, respectively, indicated... 

Imagine that a mixture of zinc, silver, and copper ions (Zn2+, Ag+, Cu2+) is thought to be present in a chip of paint taken from a work of art. Write a procedure for using a qualitative analysis scheme to detect these ions in the paint chip. Use reference books to find a substance that will form a precipitate with silver and not with copper and zinc. Next, a substance is needed to form a complex ion with copper, leaving the zinc in solution. 

The halides of all the metals except silver, lead, mercurous mercury, and cuprous copper are soluble in water, but with the ions of these metals, the halide ions give characteristic precipitates. The precipitates are valuable as tests for identifying either the halogens or the metals in qualitative analysis. 

Qualitative Analysis.—Useful information as to the suitability of water for various purposes may be rapidly obtained by means of a few qualitative tests. The presence of chloiides is revealed by addition of a few drops of concentrated silver nitrate solution acidified with nitric acid, when a white haze or turbidity results. 

Fusion of silicides Metallic silicides and carborundum are rarely encountered in routine qualitative analysis. They are best brought into solution by fusion with sodium or potassium hydroxide in a silver crucible (CAUTION) ... 

It is usual, in systematic qualitative analysis, to remove silver, lead,... 

In quantitative, as in qualitative, analysis, covalently bonded halogen must be converted into halide ion. The organic compound is heated either (a) in a bomb with sodium peroxide or (b) in a sealed tube with nitric acid (Carius method), The halide ion thus formed is converted into silver halide, which can be weighed. 

Titration with silver nitrate monitored visually for qualitative analysis or using... 

Experiments, such as qualitative analysis of ions via precipitation with a cation or anion [3], the isolation of banana (or strawberry) DNA [4], creating a DNA alias [5], coagulation of milk [6], examining reactions for exothermic or endothermic properties [7], follens test for aldehydes [8] and the conversion of copper pennies to silver [9] have been completed by the participating students. 

The most serious defect in the system, especially in its usefulness in the laboratory, is that similar elements are sometimes in remote positions, while dissimilar elements are brought close together. These difficulties are most pronounced in qualitative analysis, in which the solubilities of salts are of prime importance. As illustrations of this defect it may be observed that copper and mercury, silver and thallium, barium and lead, have many similar properties which are not suggested by their positions ixi the table. On the other hand we might expect gold and caesium, rubidium aud silver, and manganese and chlorine to resemble each other much more closely than they do. It is obvious, however, that no table could possibly show all the resemblances and contrasts of each dement, and a, detailed study of each of these elements justifies in a measure its usual position in the table. 

Color staining of the gel with GELCODE reveals protein patterns which are easily interpreted for qualitative analysis. The color aids in the analysis by distinguishing overlapping spots or bands which inherently have similar or identical isoelectric points or molecular weights. Quantitative analysis of color silver stained gel... 

Analytical chemistry began in the late eighteenth century with the work of French chemist Antoine-Laurent Lavoisier and others the discipline was further developed in the nineteenth century by Carl Fresenius and Karl Friedrich Mohr. As a pharmacist s apprentice in Frankfurt, Germany, Fresenius developed an extensive qualitative analysis scheme that, when it was later published, served as the first textbook of analytical chemistry. He built a laboratory at his house that opened in 1848. Here he trained students in gravimetric techniques that he had developed. Mohr developed laboratory devices such as the pinch clamp burette and the volumetric pipette. He also devised a colorimetric endpoint for silver titrations. It was his 1855 book on titrimetry, Lehrhuch der Chemisch-Analytischen Titromethode, that generated widespread interest in the technique. 

Wring SA, Silver IS, Serabjit-Singh CJ. Automated quantitative and qualitative analysis of metabolic stability A process for compound selection during drug discovery. Methods Enzymol 2002 357 285-296. 

The procedures and principles of qualitative analysis are covered in many introductory chemistry laboratory courses. In qualitative analysis, students learn to analyze mixtures of the common positive and negative ions, separating and confirming the presence of the particular ions in the mixture. One of the first steps in such an analysis is to treat the mixture with hydrochloric acid, which precipitates and removes silver ion, lead(II) ion, and mercury(I) ion from the aqueous mixture as the insoluble chloride salts. Write balanced net ionic equations for the precipitation reactions of these three cations with chloride ion. 

Coordination compounds are used extensively in qualitative analysis as a means of separating certain metal ions and also as a means of positively identifying certain unknown ions. For example, you may have performed an experiment used to identify silver ion in solution. If silver ion is present, the addition of chloride ion gives an immediate white precipitate of silver chloride. 

Qualitative analysis of the eluted fractions was carried out by silver staining. We have utilized a procedure that is optimized to allow analysis by MALDITOF microsequencing of the stained bands, if required (Shevchenko et al, 1996). If the preparation has to be used for microsequencing, the isolation by affinity chromatography on Rac-GTP matrix should be scaled up by a factor of 5 to 10 (referred to as larger preparations in the previous paragraph). 

Chapters 31 through 35 cover the analysis of the groups of cations. (Cations that create serious disposal problems are no longer included in the qualitative analysis chapters. Mercury, silver, lead, and most chromium cations have been removed.) Each chapter includes a discussion of the important oxidation states of the metals, an introduction to the analytical procedures, and comprehensive discussions of the chemistry of each cation group. Detailed laboratory instructions, set off in color, follow. Students are alerted to pitfalls in advance, and alternate confirmatory tests and cleanup procedures are described for troublesome cations. A set of exercises accompanies each chapter. 

In the qualitative analysis scheme for metal ions, a cation is usually detected by the presence of a characteristic precipitate. For example, silver ion gives a white precipitate with chloride ion. But other ions also give a white precipitate with chloride ion. Therefore, you must first subject a mixture to a procedure that separates individual ions before applying a precipitation test to any particular ion. 

Describe how you would separate the metal ions in a solution containing silver ion, copper(II) ion, and nickel(II) ion, using the sulfide scheme of qualitative analysis. 

Many students have prepared coordination compounds in prior chemistry courses but often have not fully understood or even identified them as such. For example, in the Group I qualitative-analysis scheme, lead(II), mercury(I), and silver(I) are isolated as the white precipitates PbCl2, Hg2Cl2, and AgCl, respectively. To separate the silver from the other two cations, aqueous ammonia is added to form the linear diamminesilver(I) complex, [Ag(NH3)2], as shown in Equation (6.1) ... 

Coordination compounds have a wide variety of applications. Complexes of monodentate ligands are used in qualitative analysis, identification of copper(II) and iron(II), dyes [Prussian (TurnbuU s) blue], the cyanotype printing process, the separation of gold and silver from their ores, the purification of nickel, and as fixers in black-and-white photography. 

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