Prussian blue precipitate

Metal hexacyanoruthenates possess a lower symmetry. Several compounds have highly disordered structures, especially when no alkali cations are present for charge compensation. Such a complex defect structure has been found for a completely potassium free Prussian blue precipitated very slowly from a solution in concentrated hydrochloric acid [25, 26]. Here, the structure still remains cubic face-centered however, one-third of the [M1 -1(CN)6] is vacant, randomly distributed and that space is filled with water molecules. The coordination sphere of the remaining ions is maintained... 

Small Quantities or Solutions. Wear eye protection, laboratory coat, and nitrile rubber gloves. In the fume hood, add the sodium cyanide to a solution of 1% sodium hydroxide (about 50 mL/g of cyanide). Household bleach (about 70 mL/g of cyanide) is slowly added to the basic cyanide solution while stirring. When addition of the bleach is complete, the solution can be tested for the presence of cyanide using the Prussian blue test To 1 mL of the solution to be tested, add 2 drops of a freshly prepared 5% aqueous ferrous sulfate solution. Boil this mixture for at least 60 seconds, cool to room temperature, and then add 2 drops of 1% ferric chloride solution. The resulting mixture is made acid to litmus with 6 M hydrochloric acid (prepared by adding concentrated acid to an equal volume of cold water). If cyanide is present, a deep blue precipitate will form. (Concentrations of cyanide greater than 1 ppm can be detected.) If the test is positive, add more bleach to the cyanide solution, and repeat the test. Continue until no Prussian blue precipitate is formed. Wash the solution into the drain.4 6... 

Figure 4. Roots of 25-day-old iron-stressed T3238FER (left) ana T3238fer (right) tomatoes after being placed in a nutrient solution containing 5 mg Fe/l. as FeHEDTA and 33 mg/l. K3Fe(CN)6. The dark areas on T3238FER roots (left) are Prussian blue precipitates formed when the roots reduced Fe3+ to Fe2+. The blue precipitate indicates the reduction sites.

Prussian blue, precipitated from potassium hexacyanoferrate (II) (ferro-cyanide), K4Fe(CN)g, solution by a little less than an equivalent of FeClg, is known to have the composition KFe[Fe(CN)g]. Its structure (Fig. 263) is... 

Metal hexacyanoruthenates possess a lower symmetry. Several compounds have highly disordered structures, especially when no alkali cations are present for charge compensation. Such a complex defect structure has been found for a completely potassium free Prussian blue precipitated very slowly from a solution in concentrated hydrochloric acid [25, 26]. Here, the structure still remains cubic face-centered however, one-third of the [M - (CN)(, is vacant, randomly distributed and that space is filled with water molecules. The coordination sphere of the remaining m1 -1 ions is maintained unchanged however, the mean coordination sphere of the M ions is decreased (mW(nC)4.5(H2O)i.5). No iron ions occupy interstitial positions, that is, only two types of iron environments exist. Since that special kind of Prussian blue has been the first and hitherto only Prussian blue that could be obtained as sufficiently large crystals to perform a single crystal structure analysis, practically all textbooks, and later publications present that defect structure as the real structure of Prussian blue, completely forgetting that this defect structure is an extreme that forms... 

Test for polyacrylonitrile and acrylonitrile copolymers. When a strip of cupric acetate paper that is freshly moistened with a dilute solution of benzidine in dilute acetic acid is held in the pyrolytic vapors of polyacrylo-nitrole or its copolymers, a bright blue color develops readily. In another test, if the condensed pyrolyzate of polyacrylonitrile or its copolymers is made alkaline, boiled with a trace of ferrous sulfate, and then acidified, Prussian blue precipitate is readily produced. 

The term is generally used to refer to Prussian blue precipitated onto a barium sulfate, baryte (qq.v.) or similar base. Davidson (1880) says of Brunswick, Celestial and damp blues Brunswick or Celestial Blue is made by precipitating the alumine from a solution of alum by carbonate of soda, washing the precipitate, and adding sulphate of baryta, sulphate of iron, yellow prussiate of potash, and some bichromate of potash. When dried, this mixture is known as Brunswick or celestial blue but when the sulphate of baryta is left out, and the material is not dried, it is called damp blue. Heaton (1928) lists Bnmswick blue as a current synonym, a reduced Prussian blue . Mayer (1991) also indicates that it may contain some ultramarine blue (. v.). 

Objective Identify the compounds with the help of their characteristic frequencies and the correlation charts. Spectrum 1-B belongs to a compound which gave a positive Prussian blue precipitate (color test for the presence of nitrogen). Spectrum 19-B belongs to a compound which gave a positive Beilstein test (flame test for chlorine—green). It is an extremely reactive material when in contact with moist air. 

K4[Fe(CN)6] White precipitate, turning blue rapidly Prussian blue precipitate... 

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