Ferrocyanide solution

Fig. 3. (a) Typical galvanostatic limiting-current curve for copper deposition at a copper disk in acidified CuS04 solution. The circles indicate the experimental curve. The solid curves were calculated using kinetic parameters as indicated, (b) Typical galvanostatic limiting current curve for ferricyanide reduction at a nickel electrode in equimolar ferri ferrocyanide solution with excess NaOH. [From Selman (S8).]... 

The current peaks observed when fast potential ramps are applied appear similar to the one shown in Fig. 8. The peak currents (triangles in Fig. 10) can be satisfactorily interpreted in terms of a pure-diffusion model (S10) in equimolar ferri-ferrocyanide solution,... 

Prussian blue is obtained as a dark blue precipitate by the addition of an iron(lll) salt to potassium ferrocyanide solution ... 

FIGURE 2.24 PCA scores for Pt electrode in ferrocyanide solution. Data represents six series of pulse voltammetry measurements performed with a self polishing device. A reproducible drift pattern is shown (reproduced from Olsson et ai, 2006, with permission). 

Pour 1-2 ml of an iron(III) chloride solution into each of two test tubes. Add several drops of an ammonium thiocyanate solution to one of the tubes, and a potassium hexacyanoferrate(II) (potassium ferrocyanide) solution to the other one. What happens Write the equations of the reactions. What are these reactions used for ... 

Sulphates, Copper, and Alkalies. — Boil for a few minutes a solution of 5 gm. of ferrous chloride in 10 cc. of water and 5 cc. of nitric acid (sp. gr. 1.3), dilute to 120 cc., add 20 cc. of ammonia water, and filter evaporate 50 cc. of the filtrate and ignite the residue. The weight of the latter should not exceed 0.001 gm. Slightly acidulate 20 cc. of the filtrate with hydrochloric acid and add barium nitrate solution. No change should appear. 20 cc. of the filtrate acidified with acetic acid should show no change upon addition of potassium ferrocyanide solution. 

Copper and Iron, — On acidifying 10 cc. of lead subacetate solution with 2 cc. of dilute acetic acid, and adding potassium ferrocyanide solution, a precipitate forms which should have a pure white color. 

Vanadium Ferrocyanides.—Solutions of vanadates, when treated with potassium ferrocyanide, yield a precipitate of doubtful composition.1 The compound is insoluble in mineral acids of high concentration, and a method involving its precipitation has recently been suggested for the estimation of vanadium in steels.2... 

Acidity.—With gall inks or mixed inks containing iron salts, it is necessary to eliminate the iron before determining the acidity. For this purpose, 5-xo c.c. of the ink are placed in a 100 or 200 c.c. flask, diluted somewhat with water and treated with potassium ferrocyanide solution-(quite neutral) until no further precipitate is formed. The whole is then made up to volume with water, shaken and allowed to settle, an aliquot part of the dear liquid being pipetted off and the acidity determined by titration with N-KOH solution (indicator, phenolphth dein). 

Potassium Ferrocyanide Solution. Dissolve 10.6 grams of analytical reagent grade potassium ferrocyanide in 100 ml. of water. 

Sbberellic acid to a 50-ml. volumetric flask, add 10.0 ml. of absolute alcohol, and lute to about 40 ml. with water. Add 2.0 ml. of zinc acetate solution, followed, after 2 minutes, by 2.0 ml. of potassium ferrocyanide solution. Adjust the contents of the flask to 50 ml. with water, mix, allow the flask to stand at room temperature for 5 minutes, and filter the contents through a Whatman No. 52 filter paper. Transfer 10.0-ml. aliquots of the filtrate to each of two 100-ml. volumetric flasks and add 8.0 ml. of absolute alcohol to each. Complete die determination as described above commencing with the addition of dilute hydrochloric acid (30%) to the first (sample) flask. 

In amperometric titrations a potential is applied across a pair of electrodes and its value is adjusted so that current flows when either analyte or titrant is present in excess. This technique has been used to a limited extent in speciation studies. Typical determinations include titration of organo-metallics, such as R2Sn2+ with standard quinolin-8-ol reagent or R2Pb2+ with ferrocyanide solution or Rfl b 1 with tetraphenylboron solution. The methods distinguish between classes of compounds without identifying the alkyl (R) groups. 

Example 4.1 A rotating ring-disk electrode (1600 rpm) yields a disk current of 12.3 pA for the oxidation of a 2 x 10 3M potassium ferrocyanide solution. Calculate the reduction current observed at the surrounding ring using a 6 x 10 3M potassium ferrocyanide solution and a rotation speed of 2500 rpm (N = 0.33). 

Here we report the efficient spectral sensitization of Ti02 by surface derivatization with a series of transition metal cyanides. The sensitization of Ti02 when treated with a ferrocyanide solution is described in a recent publication from this laboratory (Vrachnou E., Vlachopoulos N., and Gratzel M., 1987). There is evidence that the active species formed on the surface is a titanium analogue of Prussian blue. 

Potassium cuproferrocyanide, K2Cu2Fe(CN)6, is prepared 1 by boiling cuprous cyanide with a solution of potassium ferrocyanide containing a little potassium sulphite or by boiling cuprous chloride or potassium cuprous cyanide with potassium ferrocyanide solution. When rapidly cooled, the solution yields colourless cubes, but the crystals are liable to undergo partial oxidation, turning yellow or brown in colour. 

The density of potassium ferrocyamde solution at 8 9° C., saturated and in contact with crystals of the salt, is 1 1191,5 and at 25° C. 1 09081.6 The contractions resulting when given volumes of potassium ferrocyanide solutions are mixed with equal volumes of water have been measured by Wade.7... 

Carbon dioxide decomposes potassium ferrocyanide solution at 72° to 74° C., liberating hydrogen cyanide and precipitating ferrous potassium ferrocyanide.2 Continued passage of carbon dioxide through a boiling solution of potassium ferrocyanide results in the precipitation of ferric hydroxide and the formation of potassium carbonate and hydrogen cyanide, or its decomposition products, ammonia and formaldehyde.3... 

Potassium mercuric ferrocyanide, K2HgFe(CN)6, may be obtained as a faintly blue powder by the interaction of mercuric chloride and potassium ferrocyanide solutions.4 It is insoluble in water, but is decomposed by acids. 

Ferrous hydrogen ferrocyanide, H2Fe[Fe(CN)6], results when hydrogen ferrocyanide solution is heated to 110°-120° C.4 with exclusion of air. It readily oxidises to ferric hydrogen ferrocyanide, Fe H[Fe (CN)6].H20, which is a blue compound, insoluble in water, oxalic acid, and ammonium oxalate solutions. 

Potassium aquo ferricyanide, K2Fe(CN)5.H20, is obtained by the prolonged action of chlorine upon potassium ferrocyanide solution. At first potassium ferricyanide is formed, which undergoes further decomposition, the chlorine abstracting one (CN) group, water taking its place. Thus —1... 

Wet Tests.—The presence of iron in solution may readily be detected by a considerable number of sensitive reactions. Thus ferrous iron gives a green precipitate of ferrous hydroxide upon addition of excess of ammonium hydroxide. With potassium ferricyanide and a trace of acid, a deep blue precipitate—Turnbull s blue—is obtained. With potassium ferrocyanide a white precipitate is obtained in the entire absence of any ferric salt. Ferric iron, on the other hand, is usually characterised by its deep yellow or brown colour. Addition of concentrated hydrochloric acid deepens the colour. With excess of ammonium hydroxide, brown flocculent ferric hydroxide is precipitated. With potassium ferrocyanide solution, a deep blue colour is obtained in acid solution, whilst with potassium ferricyanide there is no action. Potassium thiocyanate gives in acid solution a deep red colour, which is not d troyed by heat. Salicylic acid gives a violet colour, provided no free mineral acid is present. 

Ferrous and ferric iron—ferricyanide and ferro-cyanide tests. To 2 (hops of sample add 3 (hops of 2Mhy(hochloric acid and 1 drop of 1% potassium ferricyanide solution. A deep blue precipitate indicates ferrous iron. Repeat the test but adding 1 drop of 1% potassiiun ferrocyanide solution. A deep... 

Fig. 10 The effect of potassium ferrocyanide on the luminescence spectra of [Ru(dip)3] in polymerized cationic micro emulsion (1)0 ppm, (2) 1 ppm, (3) 3 ppm, (4) 5 ppm, (5) 7 ppm and (6) 9 ppm. The contact time between the potassium ferrocyanide solution and the polymer film was 10 min. The insert is the Stern-Volmer plot for the quenching of [Ru(dip)3] + by potassium ferrocyanide...

Copper, Nitric Acid, etc. (Alkali Salts, Calcium). — Dilute 20 iM. of ferric chloride solution (1 1) with 100 cc. of water, fuld 25 cc. of ammonia water, and filter. On evaporating 50 cc. of the colorless filtrate and igniting the residue, the weight of the latter should not exceed 0.001 gm. On mixing 2 cc. of the filtrate with 2 cc. of concentrated sulphuric acid, and overlaying tliis mixture with 1 cc. of ferrous sulphate solution, no brown zone should form at the contact-surfaces of the two licpiids. 20 cc. of the filtrate acidulated With acetic a

potassium ferrocyanide solution. 

The FT-IR spectra of a 10 mol.dm ferrocyanide solution (at neutral pH) recorded just after irradiation are represented in Fig. 5(a) for different doses Fig. 5(b) highlights the 2090-2140 cm region of those differential spectra. The negative-going band at 2037 cm represents the loss of ferrocyanide. Just after irradiation, Fig. 5(b) shows that two peaks are observed the first one, located at 2115 cm is attributed to Fe(CN)g whereas the second one is located around 2102 cm h This band was attributed to the Fe(CN)5(OH) ion. Let us point out that the wavenumbers of the infrared bands can be relatively easily modeled using nh initio calculations and that these... 

Fig. 5. Evolution of the differential absorbance (after/before irradiation) of a 10 mol.dm potassium ferrocyanide solution as a function of the dose 275 Gy (black circles) 1275 Gy (red circles) 4000 Gy (blue circles) 5000 Gy (green circles). The spectra have been recorded just after irradiation the recording time is 24 s.

Le Caer S, Vigneron G, Renault JP, Pommeret S. (2007) Radiolysis of ferrocyanide solutions studied by infrared specttoscopy. Rad Phys Chem 76 1280-1284. 

Experiment 189. — (a) Put a few grams (3 to 5) of iron filings in a test tube, add about 10 cc. of dilute hydrochloric acid, and warm gently. Ferrous chloride is formed (in solution), (i) Pour a little into a test tube one-third full of sodium hydroxide solution. The precipitate is ferrous hydroxide. Watch the changes in color. To what are the changes due (2) Add a second portion to potassium ferricyanide solution. The precipitate is ferrous ferricyanide. Describe it. (3) Add a third portion to potassium thiocyanate solution. If ferric salts are absent, no change results. (4) Add a fourth portion to potassium ferrocyanide solution. The precipitate is ferrous ferrocyanide. Describe it. 

Test for Fe or Cu in effluent to 2 drops effluent on spot plate add 2 drop cone. HCl and 2 drops fresh S% potassium ferrocyanide solution. Blue color indicates Fe . Brown color is Cu . Most spot tests can be performed directly on the resin e.g., a particle of resin containing 2 ppm iron will turn blue when subjected to ferrocyanide tests. 

The pigments Prussian blue and TurnbulFs blue are made by addition of ferrous ion to a ferricyanide solution or ferric ion to a ferrocyanide solution. The pigments which precipitate have the approximate composition KFeFe(CN)g HoO. They have a brilliant blue color. Ferrous ion and ferrocyanide ion produce a white precipitate of KoFeFe(CN)6, whereas ferric ion and ferricyanide ion do not form a precipitate, but only a brown solution,... 

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