Potassium chloride isotherm

Figure 3. Isotherm of potassium chloride-water-THF in weight percent (invariant point 22.6% KCly71.0% H20, 6.4% THF)...

Calorimeter. A differential calorimeter, operating at 25.0 °C under near-isothermal conditions, was used for all heat measurements. Similar calorimeters, designed for determining heats of ion exchange in zeolites, have been described previously (5, 6, 14, 15). The calorimeter was calibrated by measuring the heat of solution of potassium chloride in water. The ratio of the area under the curve traced by the recorder pen to the heat produced was 1.50 dz 0.04 cm per calorie. No heat could be detected when an empty evacuated bulb was broken under water. 

The calculations have been carried out for those systems for which the solubility calculations have been performed. The dilute region of sodium chloride (c < 0.3) was selected to ensure that the condition F /x = s = constant is satisfied. The partial molar volume was estimated using literature data [67-69]. According to the latter data, depends weakly on C3 and this dependence is linear in the dilute range [68,69]. For sodium chloride and potassium chloride, decreases by at most 1 cm /mol when Cj is changed from 0 to 2mol/l. In our calculations, the above decrease was taken 1 cm /mol. On this basis the composition dependence of was evaluated in the composition range 0 < C3 < 0.3. The partial molar volumes Vi and V3 of water and sodium chloride in the binary mixture water (1) + sodium chloride (3) were obtained from data available in the literature [70,71], and the composition dependence of the isothermal compressibility of the mixed solvent (water (1) + sodium chloride (3)) was taken from reference [71]. 

Throughout its whole course, the curve EMK represents solutions in which the ratio of MgCl. KCl is greater than in the double salt. As this is a point of some importance, it will be well, perhaps, to make it clearer by giving one of the isothermal curves, e.g. the curve for 10 , which is represented diagrammatically in Fig. 131. E and F here represent solutions saturated for carnallite plus magnesium chloride hydrate, and for carnallite plus potassium chloride. As is evident, the point F lies above the line representing equimolecular proportions of the salts (OD). 

In the first place, it may be again noted that at a temperature above (point M) carnallite cannot exist. If, therefore, a solution of magnesium and potassium chlorides is evaporated at a temperature above this point, the result will be a mixture of potassium chloride and either magnesium chloride tetrahydrate or magnesium chloride dihydrate, according as the temperature is below or above 176°. The isothermal curve here consists of only two branches. 

From the information yielded by the isothermal diagrams based on the solubility data, it is possible to decide the conditions under which potassium nitrate can best be prepared by double decomposition between potassium chloride and sodium nitrate. Thus Reinders has... 

Consequently, two different temperature coefficients of the electrode potential can be obtained the isothermal and the thermal temperature coefficient. The thermodynamic implications of these coefficients were clearly established by de Bethune, who also evaluated the values of the temperature coefficients of a wide variety of reference electrodes. While the use of a non-isothermal cell presents the clear advantage that only the temperature effect on the reaction on the working electrode is evaluated, it also presents the problem that the measurements will be interfered by the appearanee of a thermodiffiision potential, arising from temperature differences within the electrolyte solution. This thermodiffusion potential can be experimentally minimized (by using, for example, a saturated potassium chloride bridge for the liquid unions) or, alternatively, the effect of the thermodiffusion potential can be subtracted by calculating its numerical value from ... 

Some of the similar data with potassium chloride instead of sodium chloride are shown in Table 2.28 (these data are also very limited). Potassium chloride is slightly more soluble than sodium chloride, but other than that, the data should be reasonably similar. Perova (1957) presented 25 and 55°C isotherms for this system with KCl instead of NaCl, and Holdorf et al (1993) plotted... 

Urine (5 ml) urine spiked with 0.2% (v/v) isopropylamine is placed in a screw-capped 15-ml vial [28]. Pelleted potassium hydroxide (3 g) is added before sealing the vial with an airtight polytetrafluoroethylene-lined septum cap. Potassium hydroxide raises the pH of the sample to ensure that the amines are present as volatile bases. The vial is heated in an aluminium block at 90 C for 20 min. While still in this block, 2 ml head-space gas is withdrawn through the septum with a disposable syringe and injected immediately on the gas chromatography column. The operating temperatures of the column, injector port and detector unit are 70 C isothermal, 150 C and 200 C, respectively, with nitrogen carrier gas at 60 ml/min. This allows quantification of TMA and other amines. TMA N-oxide is measured after quantitative reduction into TMA. For this, titanous chloride (30%, w/v 0.2 ml) is added to 2 ml urine in a screw-capped vial and incubated for 30 min at room temperature. The sample is then diluted ten-fold with distilled water and analysed as described above. The result represents the sum of TMA and TMA N-oxide present in the sample. 

Fig. 6. Isothermal phase transitions from the phase separated to homogeneous state of the aqueous solution of the copolymer containing 11.6 mol % pendant crown ether groups by the addition of (O) potassium and (9) sodium chlorides at 32 °C and 37 °C. Polymer concentration was 1 mass %...

Space Model for Camallite.—Interesting and important as the isothermal solubility curves are, they are insufficient for the purpose of obtaining a clear insight into the complete behaviour of the systems of two salts and water. A short description will, therefore, be given here of the representation in space of the solubility relations of potassium and magnesium chlorides, and of the double salt which they form, carnallite, ... 

The heats of formation of potassium, rubidium, and caesium hexachlorotellu-rates(iv) have been found from their heats of solution, and those of crystalline TeCU and the metal chlorides determined from isothermal calorimetry. Thermal and elastic properties of the alkali-metal hexachlorotellurates have also been investigated. Spectroscopic studies on a series of dialkyltellurium tetraiodides have been carried out. ... 

The mixtures were equilibrated isothermally for 5 hours while being stirred by a stream of inert gas. The potassium content was determined by using a flame photometer, the dihydrogenphosphate was determined acldlmetrlcally using thymolphthaleln as indicator, and chloride was determined mercurimetrically. 

The Isothermal method was used. Equilibrium was checked by repeated analysis. Standard analytical methods were used to determine the amount of chloride, potassium and dihydrogenphosphate ions. 

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