Potassium estimation

Andrews deration An important titration for the estimation of reducing agents. The reducing agent is dissolved In concentrated hydrochloric acid and titrated with potassium iodale(V) solution. A drop of carbon tetrachloride is added to the solution and the end point is indicated by the disappearance of the iodine colour from this layer. The reducing agent is oxidized and the iodate reduced to ICl, i.e. a 4-eiectron change. 

Fehling s solution A solution of copper sulphate, sodium potassium tartrate and NaOH used for estimating and detecting reducing sugars. 

A first approach to testing, ASTM D 1094, is to create, using a potassium phosphate reagent, a separation between two layers, hydrocarbon and aqueous. The degree of separation of the two phases is estimated by attributing a grade from 1 to 3 and the appearance of the interface by five levels of observation 1, lb, 2, 3, and 4. The specifications establish both the quality of separation (2 is the maximum) and the appearance of the interface (lb maximum). 

The reaction with acidified potassium manganate(VII) is used in the quantitative estimation of hydrogen peroxide. 

Addition of silver nitrate to a solution of a chloride in dilute nitric acid gives a white precipitate of silver chloride, AgCl, soluble in ammonia solution. This test may be used for gravimetric or volumetric estimation of chloride the silver chloride can be filtered off, dried and weighed, or the chloride titrated with standard silver nitrate using potassium chromate(VI) or fluorescein as indicator. 

Excess standard acid is added, and the excess (after disappearance of the solid oxide) is estimated by titration with standard potassium manganate(VII). 

Silver nitrate is used volumetrically to estimate chloride, bromide, cyanide and thiocyanate ions. Potassium chromate or fluorescein is used as an indicator. 

Both chloramine-T and dichloramine-T can be readily estimated, because they liberate iodine from potassium iodide quantitatively in the presence of... 

Note. (1) Most sulphur compounds are completely oxidised if the tube is heated under the conditions described for the estimation of halogens. Sul-phonic acids and sulphones are more difficult to oxidise completely and the tube should be slowly heated to 300 and maintained at this temperature for at least 6 hours. The oxidation may be facilitated by adding a few crystals of sodium or potassium bromide to the organic material in the small tube, so that bromine shall be present to intensify the oxidation during the heating. 

Noth. The above method can be successfully applied only to dilute solutions of formaldehyde which are free in particular from other alfphatic aldehydes, since the latter, if present, would undergo a similar oxidation. Formaldehyde, if mixed with other aldehydes, should be estimated by quantitative addition of potassium cyanide for details, see advanced text-books of quantitative organic analysis. 

Digestion. 20-25 mg. of the substance whose nitrogen content is to be estimated are weighed out in a stoppered weighing-tube and then transferred to the flask L that has been previously dried in an oven at izo C. With care, the substance may be transferred directly into the bulb of the flask without any adhering to the sides. If any material sticks on the way down, the flask should be tapped gently to cause the substance to fall to the bottom. 2 G. of the catalyst mixture (32 g. of potassium sulphate, 5 g. of mercury sulphate and ig. of selenium powder, well mixed) are added and 3 ml. of A.R. cone, sulphuric acid are measured out carefully and poured into the digestion... 

Into a 750 ml. round-bottomed flask furnished with a reflux condenser place a solution of 34 g. (18-5 ml.) of concentrated sulphuric acid in 100 ml, of water add 33 g. of di-n-butyl cyanamide and a few fragments of porous porcelain. Reflux gently for 6 hours. Cool the resulting homogeneous solution and pour in a cold solution of 52 g. of sodium hydroxide in 95 ml. of water down the side of the flask so that most of it settles at the bottom without mixing with the solution in the flask. Connect the flask with a condenser for downward distillation and shake it to mix the two layers the free amine separates. Heat the flask when the amine with some water distils continue the distillation until no amine separates from a test portion of the distillate. Estimate the weight of water in the distillate anp add about half this amount of potassium hydroxide in the form of sticks, so that it dissolves slowly. 

From the radioactive decay constants and measurement of the amount of argon in a rock sample, the length of time since formation of the rock can be estimated. Essentially, the dating method requires fusion of a rock sample under high vacuum to release the argon gas that has collected through radioactive decay of potassium. The amount of argon is determined mass spectrometrically,... 

Industrial Hquid chlorine is routinely analy2ed for moisture, chlorine, other gaseous components, NCl, and mercury foUowing estabHshed procedures (10,79). Moisture and residue content in Hquid chlorine is determined by evaporation at 20°C foUowed by gravimetric measurement of the residue. Eree chlorine levels are estimated quantitatively by thiosulfate titration of iodine Hberated from addition of excess acidified potassium iodide to the gas mixture. 

K2SO-2 MgSO, and halite and (5) kainite ore, kainite [1318-72-5] 4(KC1 MgSO -11H20, and halite. More than 90% of the estimated potassium reserves occur principally as sylvinite and camaUitite (107). Sylvite, the richest of the minerals at 63% K2O, is the principal economically exploitable reserve. In addition, there are four principal insoluble potassium sUicate minerals, glauconite, leucite, nepheline, and orthoclase—sanidine which range in K2O content from 7 to 22%. These minerals are plentihil but for economic reasons may never be exploited for potassium. 

An assessment of world potash resources (108) is shown in Table 15. Of the 67 x 10 t of total estimated reserves and resources in Canada, nearly 5 X 10 t is recoverable by conventional mining methods and the remainder by solution mining. As of 1974, Canada had about half of the known world reserves and about 90% of known world resources of potassium. 

Economic Aspects. The estimated total worldwide market for tartaric acid is 58,000 t and potassium bitartrate (acid basis) is 20,000 t. The majority of tartaric acid consumption, represented by beverage, food, and pharmaceutical appHcations, is shown in Table 10. Potassium bitartrate (cream of tartar) is primarily used in baking powders and mixes. 

O ne. Air pollution (qv) levels are commonly estimated by determining ozone through its chemiluminescent reaction with ethylene. A relatively simple photoelectric device is used for rapid routine measurements. The device is caHbrated with ozone from an ozone generator, which in turn is caHbrated by the reaction of ozone with potassium iodide (308). Detection limits are 6—9 ppb with commercially available instmmentation (309). 

Total world capacity for electrolytic manganese dioxide (FMD) is estimated to be in the area of 194, 500 t/yr, and aimual capacity of chemical manganese dioxide (CMD) is estimated to be in the range of 40,000 t. Producers are fisted in Tables 18 and 19, respectively. Capacity and process information on potassium permanganate is given in Table 17. 

In 1840, potassium was recognized as an essential element for plant growth (6). This discovery and the invention in 1861 of a process to recover potassium chloride from mbbish salt, a waste in German salt mines, started the modem potassium chemical industry (5). Potassium compounds produced throughout the world in 1993 amounted to ca 22 million metric tons as K O equivalent (4), down from ca 24 million t in 1992, having fallen annually from 32 million t in 1989 (2). Estimated production capacity was between 29 and 32 million t in 1992 (2). 

The estimation of alkoxy groups is not such a simple task. One method (26,68) involves hydrolysis and oxidation of the Hberated alcohol with excess standard potassium dichromate solution. The excess may then be estimated iodometrically. This method is suitable only for methoxides, ethoxides, and isopropoxides quantitative conversion to carbon dioxide, acetic acid, and acetone, respectively, takes place. An alternative method for ethoxides is oxidation followed by distillation, and titration of the Hberated acetic acid. 

Economic Aspects. Capacity for sodium thiocyanate in the United States is substantially the same as that for ammonium thiocyanate because both products can be made in the same plants, but production is estimated at only slightly over 1000 t. The rate of growth is slight. The price on a 100 wt % basis in 1995 was 2.10/kg. Most sodium thiocyanate is sold as the solution. Potassium thiocyanate is a much lower volume product. 

The concentration of dissolved ionic substances can be roughly estimated by multiplying the specific conductance by an empirical factor of 0.55—0.9, depending on temperature and soluble components. Since specific conductance is temperature dependent, all samples should be measured at the same temperature. Alternatively, an appropriate temperature-correction factor obtained by comparisons with known concentrations of potassium chloride may be used. Instmments are available that automatically correct conductance measurements for different temperatures. 

Chloroform may be estimated quantitatively by determining the amount of copper oxide produced when it is warmed with Fehling s solution, which is potassium cupritartrate (34). An alternative procedure consists of heating the chloroform with concentrated alcohoHc potassium hydroxide in a sealed tube at 100°C and determining the amount of potassium chloride produced (35). 

Potassium cyanide [151 -50-8] KCN, a white crystalline, deUquescent soHd, was initially used as a flux, andlater for electroplating, which is the single greatest use in the 1990s. The demand for potassium cyanide was met by the ferrocyanide process until the latter part of the nineteenth century, when the extraordinary demands of the gold mining industry for alkah cyanide resulted in the development of direct synthesis processes. When cheaper sodium cyanide became available, potassium cyanide was displaced in many uses. With the decline in the use of alkah cyanides for plating the demand for potassium cyanide continues to decline. The total world production in 1990 was estimated at about 4500 t, down from 7300 t in 1976. 

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