Saturated Potassium

Many of the Vargaftik values also appear in Ohse, R. W., Handbook of Thermodynumie and Transport Froperties of Alkali Metals, Blackwell Sci. Pubs., Oxford, 1985 (1020 pp.). This source contains superheat data. Saturation and superheat tables and a diagram to 30 bar, 1650 K are given by Reynolds, W. C., Thermodynamic Froperties in S.L, Stanford Univ. pubk, 1979 (173 pp.). For aMollier diagram from 0.1 to 250 psia, 1300 to 2700°R, see Weatherford, W. D., J. C. Tyler, et ah, WADD-TR-61-96,1961. An extensive review of properties of the solid and the saturated liquid is given by Alcock, C. B., M. W. Chase, et ak, /. Fhys. Chem. Ref Data, 23, 3 (1994) 385-497. 

17 Mollier diagram for potassium. Basis enthalpy = 0.0 cal/g atom at 298 K entropy = 15.8 cal/(g atom-K) at 298 K. (Aerajet-GeTwral Rep. AGN8194, ml 

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Tetrasubstituted phosphonium halides are just as effective as their ammonium counterparts. A combination of tetraphenylphosphonium bromide and either 18-crown-6 or polyethylene glycol dimethyl ether with spray-dried potassium fluoride converts 4-chlorobenzaldehyde to 4-fluorobenzaldehyde in 74% yield [67] In addition, the halogen of a primary alkyl chloride or bromide is easily displaced by fluorine in aqueous saturated potassium fluoride and a catalytic amount of hexadecyltributylphosphonium bromide [68] (Table 7 Procedure 4, p 194)... 

The filtrate is treated with excess hydrochloric acid and evaporated to obtain a pale yellow oil. Five grams of the oil thus obtained is treated with 15 cc of saturated potassium carbonate solution and the mixture extracted with 50 cc of ether, then with 30 cc of ethyl acetate and finally with two 30 cc portions of ethanol. Evaporation of the solvent from the extract gives the following quantities of the desired 1-phenyl-2-aminopropane-1,3-diol 0.5 g, 1.0 g and 3.1 g. 

The most widely used reference electrode, due to its ease of preparation and constancy of potential, is the calomel electrode. A calomel half-cell is one in which mercury and calomel [mercury(I) chloride] are covered with potassium chloride solution of definite concentration this may be 0.1 M, 1M, or saturated. These electrodes are referred to as the decimolar, the molar and the saturated calomel electrode (S.C.E.) and have the potentials, relative to the standard hydrogen electrode at 25 °C, of 0.3358,0.2824 and 0.2444 volt. Of these electrodes the S.C.E. is most commonly used, largely because of the suppressive effect of saturated potassium chloride solution on liquid junction potentials. However, this electrode suffers from the drawback that its potential varies rapidly with alteration in temperature owing to changes in the solubility of potassium chloride, and restoration of a stable potential may be slow owing to the disturbance of the calomel-potassium chloride equilibrium. The potentials of the decimolar and molar electrodes are less affected by change in temperature and are to be preferred in cases where accurate values of electrode potentials are required. The electrode reaction is... 

Some commercial electrodes are supplied with a double junction. In such arrangements, the electrode depicted in Fig. 15.1(h) is mounted in a wider vessel of similar shape which also carries a porous disc at the lower end. This outer vessel may be filled with the same solution (e.g. saturated potassium chloride solution) as is contained in the electrode vessel in this case the main function of the double junction is to prevent the ingress of ions from the test solution which may interfere with the electrode. Alternatively, the outer vessel may contain a different solution from that involved in the electrode (e.g. 3M potassium nitrate or 3M ammonium nitrate solution), thus preventing chloride ions from the electrode entering the test solution. This last arrangement has the disadvantage that a second liquid junction potential is introduced into the system, and on the whole it is preferable wherever possible to choose a reference electrode which will not introduce interferences. 

This electrode is perhaps next in importance to the calomel electrode as a reference electrode. It consists of a silver wire or a silver-plated platinum wire, coated electrolytically with a thin layer of silver chloride, dipping into a potassium chloride solution of known concentration which is saturated with silver chloride this is achieved by the addition of two or three drops of 0.1M silver nitrate solution. Saturated potassium chloride solution is most commonly employed in the electrode, but 1M or 0.1 M solutions can equally well be used as explained in Section 15.1, the potential of the electrode is governed by the activity of the chloride ions in the potassium chloride solution. 

Glass electrodes are now available as combination electrodes which contain the indicator electrode (a thin glass bulb) and a reference electrode (silver-silver chloride) combined in a single unit as depicted in Fig. 15.2(h). The thin glass bulb A and the narrow tube B to which it is attached are filled with hydrochloric acid and carry a silver-silver chloride electrode C. The wide tube D is fused to the lower end of tube B and contains saturated potassium chloride solution which is also saturated with silver chloride it carries a silver-silver chloride electrode E. The assembly is sealed with an insulating cap. 

PI. Saturated potassium hydrogentartrate solution. The pH is insensitive to changes of concentration and the temperature of saturation may vary from 22 to 28 °C the excess of solid must be removed. The solution does not keep for more than a few days unless a preservative (crystal of thymol) is added. 

The H-type cell devised by Lingane and Laitinen and shown in Fig. 16.9 will be found satisfactory for many purposes a particular feature is the built-in reference electrode. Usually a saturated calomel electrode is employed, but if the presence of chloride ion is harmful a mercury(I) sulphate electrode (Hg/Hg2 S04 in potassium sulphate solution potential ca + 0.40 volts vs S.C.E.) may be used. It is usually designed to contain 10-50 mL of the sample solution in the left-hand compartment, but it can be constructed to accommodate a smaller volume down to 1 -2 mL. To avoid polarisation of the reference electrode the latter should be made of tubing at least 20 mm in diameter, but the dimensions of the solution compartment can be varied over wide limits. The compartments are separated by a cross-member filled with a 4 per cent agar-saturated potassium chloride gel, which is held in position by a medium-porosity sintered Pyrex glass disc (diameter at least 10 mm) placed as near the solution compartment as possible in order to facilitate de-aeration of the test solution. By clamping the cell so that the cross-member is vertical, the molten... 

The potential developed is determined by the chloride concentration of the inner solution, as defined by the Nemst equation. As can been seen from the above reaction, the potential of the electrode remains constant as long as the chloride concentration remains constant. Potassium chloride is widely used for the inner solution because it does not generally interfere with pH measurements, and the mobility of the potassium and chloride ions is nearly equal. Thus, it minimizes liquid-junction potentials. The saturated potassium chloride is mainly used, but lower concentrations such as 1M potassium chloride can also be used. When the electrode is placed in a saturated potassium chloride solution, it develops a potential of 199 mV vs the standard hydrogen electrode. 

Griesheim (1) An early process for producing chlorine by electrolysis, developed by Chemische Fabrik Griesheim-Elektron, in Germany, and commercialized in 1890. The electrolyte was saturated potassium chloride solution, heated to 80 to 90°C. The byproduct potassium hydroxide was recovered. The process was superseded in the United States by several similar electrolytic processes before being ousted by the mercury cell, invented by H. Y. Castner and K. Kellner in 1892. See Castner-Kellner. 

The work-up was done by dropwise addition of ice-cold water (50 mL caution gas evolution ). The reaction mixture was diluted with dichloromethane (lOOmL) and washed with saturated potassium carbonate solution (2 x 50 mL) and brine (2 x 50 mL). The organic layer was dried over magnesium sulfate, filtrated and concentrated using a rotatory evaporator. 

Charlie Focht of the Nebraska State Agriculture Laboratory refills a saturated calomel electrode with saturated potassium chloride while preparing to analyze animal feed samples for sodium chloride via a poten-tiometric titration. 

Hexane (100 mL) is added to the reaction mixture causing more white precipitate to form. The mixture is filtered by suction, and the collected solids are washed with two 50-mL portions of hexane. The combined filtrate and washings are partitioned with 200 mL of a mixture (1 3 v/v) of saturated potassium carbonate solution and water (Note 8). The aqueous phase is extracted with three 200-mL portions of hexane. The combined organic phases are partitioned with 100 mL of saturated sodium chloride, dried thoroughly over anhydrous sodium sulfate and concentrated under reduced pressure to afford 65-75 g of crude product. A small amount of additional crude material can be isolated by continuously extracting the combined aqueous layers with hexane for 3 hr. 

When saturated potassium sulfate solution is used, the potential is 0.64 V versus NHE and 0.40 V versus SCE. The relationships between reference electrodes discussed above are shown in Eigure 5.8. 

Carbomethoxytropinone. A mixture of 1.35 g of sodium methoxide (this is sodium in a minimum amount of methanol), 3.5 g of tropinone, 4 ml of dimethylcarbonate and 10 ml of toluene is refluxed for 30 min. Cool to 0° and add 15 ml of water that contains 2.5 g of ammonium chloride. Extract the solution after shaking with four 50 ml portions of chloroform, dry, evaporate the chloroform in vacuo. Dissolve the oil residue in 100 ml of ether, wash twice with a mixture of 6 ml of saturated potassium carbonate and three ml of 3 N KOH. Dry and evaporate in vacuo to recover the unreacted tropinone. Take up the oil in a solution of aqueous ammonium chloride and extract with chloroform, dry, and evaporate in vacuo to get an oil. The oil is dissolved in hot acetone, cool, and scratch inside of flask with glass rod to precipitate 2-carbomethoxytropinone. Recrystallize 16 g of this product in 30 ml of hot methyl acetate and add 4 ml of cold water and 4 ml of acetone. Put in freezer for 2 /2 to 3 hours. Filter and wash the precipitate with cold methyl acetate to get pure product. 

The potential of this electrode only depends on the chloride ion concentration which is strictly controlled by the saturated potassium chloride solution in the electrode. The E° value for the above reaction is 0.26808 volts (at 273.15 K and a pressure of 1 atm (or, 101325 Pa). 

After prerinsing for 5 min, samples of about 50 ml should be taken from the sample point of the returning water, after which a few drops of a saturated potassium chloride solution should be added. Then pH can be measured. 

HC1 w/saturated potassium persulfate 1% N8311 /0.2 K0H Argon Carrier Gas... 

Iodometric titration was carried out as shown below About 100 mg. of hydroxylamine-O-sulfonic acid was exactly weighed and dissolved in 20 ml. of distilled water. Sulfuric acid (10 ml. of 10% solution) and 1 ml. of saturated potassium iodide solution were then added. After the solution was allowed to stand for 1 hour, liberated iodine was titrated with 0.1 N sodium thiosulfate solution until the iodine color disappeared. The following stoichiometric relation was used 0.1 N Na2S203 (1 ml.) = 5.66 mg. H3NOSO3. Hydroxylamine-O-sulfonic acid should be stored in tightly sealed bottles in a refrigerator. 

Thoroughly wash a burette with a chromium mixture and water, and then rinse it two or three times with the prepared saturated potassium dichromate solution. Why is this done Fasten the burette in a stand and pour the transparent solution into it. Fill the tip of the burette with the solution and note the level of the liquid in the burette. 

Preparation of Bromine by Displacing It from Its Salts. Pour 2-3 ml of a saturated potassium bromide solution into a test tube and pass a strong stream of chlorine through it. What occurs Distil off the prepared bromine into a receiver test tube (see Fig. 55). Write the equation of the reaction. Can chlorine and iodine be prepared in this way ... 

Add 3-5 ml of water into a test tube with bromine and stir its contents with a glass rod. What is observed Is the solubility of bromine in water high What is called bromine water Add a few drops of a saturated potassium bromide solution to this tube containing bromine water and stir its contents. Explain what occurs. 

Pour 5 ml of a saturated potassium iodide solution into a test tube. Pass a stream of chlorine through the solution. What substance evolves Filter the substance on a smooth filter and dry it in the air. What impurity will the iodine contain How can it be purified ... 

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