Atomic potassium, fractionation

Figure 2. Isotopic fractionation curves computed from Kanno (12) for the vaporization of atomic potassium and potassium compounds. The absolute ratio (13.8566 + O.OO63) is denoted by the...

Figure 7.21. Fraction of unoccupied sites, and of sites occupied by atomic nitrogen and NH, as a function of reactor length on a potassium-promoted iron ammonia catalyst at 673 K,...

Elution volume calibrations were performed using radioactive tracers of the rare earth elements and 133Ba, with atomic-absorption or flame-emission analysis of iron, sodium, potassium, calcium, and magnesium. As shown in Fig. 5.14, any barium added to the second columns is eluted at the start of the light rare earth element fraction . To ensure barium removal the sample can be put through the first column again. 

Then the expression for the weighted-average atomic mass is used, with the percent abundances converted to fractional abundances by dividing by 100. The average atomic mass of potassium is 39.0983 u. 

A second type of interference is ionization interference. Certain elements, particularly the alkali metals in high temperature flames, become partially ionized in the flame. This event causes a decrease in the number of neutral atoms and hence, a decrease in the sensitivity. For example, an appreciable fraction of sodium atoms will be ionized. Now if another easily ionized element such as potassium is added to the sodium solution, it will contribute free electrons to the flame and cause the equilibrium for the sodium ionization to shift toward the formation of a larger fraction of neutral atoms. This is, therefore, a positive interference. It can be overcome by adding the same amount of interfering element to the standard solution. Or, more simply, a large amount of an ionizable element such as potassium (200 to 1000 ppm) can be added to both sample and standard solutions this will effectively suppress ionization to a small and constant value and at the same time increase the sensitivity. 

Fig. 12.13 shows the extent of the secondary flame zone as a function of the concentration of KNO3 at a chamber pressure of 4 MPa and with Dt = 5.0 mm with nozzle area expansion ratios of e = 6.3 and 11.7. No clear difference is seen for the different values of 8. It is evident that the zone shrinks with increasing concentration of KNO3 and thus also with increasing mass fraction of potassium atoms contained within the propellant Fig. 12.14 shows the extent of the secondary flame zone as a function of the concentration of K2SO4 at a chamber pressure of 4 MPa with D, = 5.0 mm and e = 1. Like KNO3, K2SO4 is seen to be effective as a plume sup-... 

To a flask containing 45 ml (0.77 mole) of absolute ethanol is added portion-wise 2.5 gm (0.11 gm-atom) of sodium metal. While stirring vigorously and cooling, 9.55 gm (0.05 mole) of 2,2-dichlorobenzo-l,3-dioxolane in 25 ml of ether is added dropwise. After 18 hr the salt is filtered off, the filtrate diluted with ether, washed with cold water, dried over potassium carbonate, and fractionally distilled to afford 6.4 gm (60%), b.p. 123°C (15 mm), 1.4943. 

Note that it is sometimes convenient to represent a fractional number of molecules in an equation.) We see that 1 gram formula weight of KCIO3, 122.5 g, should liberate 3 gram-atoms of oxygen, 48.0 g. Hence the amount of oxygen that should be liberated from 2.00 g of potassium chlorate is X 2.00 = 0.786 g. 

In a 5-1. round-bottomed flask fitted with a large-bore reflux condenser are placed 200 g. (230 ml., 0.65 mole) of ethyl oleate (Note 1) and 1.5 1. of absolute ethanol (Note 2). Through the reflux condenser is added 80 g. (3.5 gram atoms) of sodium rapidly enough to keep up a vigorous reaction. The flask is shaken occasionally. After the initial reaction has subsided, about 200 ml. more of absolute alcohol is added, and the mixture is heated on a steam bath until all the sodium has reacted. Then 500 ml. of water is added, and the mixture is refluxed for 1 hour to saponify the unreacted ester. The mixture is cooled, and 1.2 1. of water is added. The unsaponifiable fraction is extracted with ether, and the extracts are washed with 1% potassium hydroxide solution and then with water till free of alkali when tested externally with phenolphthalein. The ether extract is dried over sodium sulfate, the ether removed by distillation, and the residue distilled through an efficient column (Note 3). A yield of 84-89 g. (49-51%), b.p. 150-152°/ mm., is obtained. 

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