Potassium iron periodate

J. Sugar, C. Corliss Atomic energy levels of the iron-period elements Potassium through Nickel, Phys. Chem. Ref. Data 14, Suppl. 2 (1985)... 

Reagents, such as aluminum hydroxide [119-121, 124], potassium, and iron periodates [118] have been successfully applied for lithium coprecipitation. In the last case, ion exchange was used to concentrate lithium after dissolution of the coprecipitate. 

Sugar, J. and Corliss, C., Atomic Energy Levels of the Iron Period Elements Potassium through Nickel, /. Phys. Chem. Ref Data, Vol.l4, Suppl. 2,1985. 

Atomic radius increases as we go from top to bottom or right to left in the periodic table. Sulfur and selenium are both in Group 16 because sulfur is above selenium, it will be smaller. Similarly, the positions of rubidium and potassium in Group 1 tell us that potassium is the smaller of the two. Finally, potassium, iron, and selenium are in the fourth period. Selenium is the rightmost of the three, so it will be the smallest, followed by iron and then potassium. Putting all these facts together gives us the requested order S < Se < Fe < K < Rb. 

Periodates give precipitates with solutions of ferric salts and also with most of the tervalent and quadrivalent metals. These precipitates are soluble in excess potassium hydroxide and periodate. When iron periodate dissolves in alkali hydroxide, there probably is formed an alkali salt of iron para-periodic acid with the anion [lOeFe]-. Most of the reactions of iron appear to be masked in the solutions of this alkali salt. The alkaline solution of the iron periodate complex is a selective reagent for lithium, which alone among the alkali metals is precipitated, even from dilute solutions and in the cold. The composition of the yellow-white product depends on the experimental conditions with excess of alkali periodate, the ratio of the components is 1 lithium 2 periodic acid. 

Reagent Alkaline iron periodate solution 2 g potassium periodate is dissolved in 10 ml of 2 AT KOH (freshly prepared), diluted to 50 ml water and mixed with 3 ml of 10 % FeClg solution and made up to 100 ml with 2 N KOH. The reagent is stable. 

Silicon [7440-21-3] Si, from the Latin silex, silicis for flint, is the fourteenth element of the Periodic Table, has atomic wt 28.083, and a room temperature density of 2.3 gm /cm. SiUcon is britde, has a gray, metallic luster, and melts at 1412°C. In 1787 Lavoisier suggested that siUca (qv), of which flint is one form, was the oxide of an unknown element. Gay-Lussac and Thenard apparently produced elemental siUcon in 1811 by reducing siUcon tetrafluoride with potassium but did not recognize it as an element. In 1817 BerzeHus reported evidence of siUcon occurring as a precipitate in cast iron. Elemental siUcon does not occur in nature. As a constituent of various minerals, eg, siUca and siUcates such as the feldspars and kaolins, however, siUcon comprises about 28% of the earth s cmst. There are three stable isotopes that occur naturally and several that can be prepared artificially and are radioactive (Table 1) (1). 

Strontium [7440-24-6] Sr, is in Group 2 (IIA) of the Periodic Table, between calcium and barium. These three elements are called alkaline-earth metals because the chemical properties of the oxides fall between the hydroxides of alkaU metals, ie, sodium and potassium, and the oxides of earth metals, ie, magnesium, aluminum, and iron. Strontium was identified in the 1790s (1). The metal was first produced in 1808 in the form of a mercury amalgam. A few grams of the metal was produced in 1860—1861 by electrolysis of strontium chloride [10476-85-4]. 

During the lifetime of a root, considerable depletion of the available mineral nutrients (MN) in the rhizosphere is to be expected. This, in turn, will affect the equilibrium between available and unavailable forms of MN. For example, dissolution of insoluble calcium or iron phosphates may occur, clay-fixed ammonium or potassium may be released, and nonlabile forms of P associated with clay and sesquioxide surfaces may enter soil solution (10). Any or all of these conversions to available forms will act to buffer the soil solution concentrations and reduce the intensity of the depletion curves around the root. However, because they occur relatively slowly (e.g., over hours, days, or weeks), they cannot be accounted for in the buffer capacity term and have to be included as separate source (dCldl) terms in Eq. (8). Such source terms are likely to be highly soil specific and difficult to measure (11). Many rhizosphere modelers have chosen to ignore them altogether, either by dealing with soils in which they are of limited importance or by growing plants for relatively short periods of time, where their contribution is small. Where such terms have been included, it is common to find first-order kinetic equations being used to describe the rate of interconversion (12). 

In the electrolytic process, a fused mixture of anhydrous rare earth chlorides (obtained above) and sodium or potassium chloride is electrolyzed in an electrolytic cell at 800 to 900°C using graphite rods as the anode. The cell is constructed of iron, carbon or refractory hnings. Molten metal settles to the bottom and is removed periodically. 

Fig. 3.14 Square-wave voltammograms of PlGEs modified with sample Cl-12 from abronze mon-tefortino helmet from the Gabriel river valley (Kehn and Ikalesken period) in the Valencian region of Requena, dating back to the Second Iron Age. Electrolyte 0.50 M potassium phosphate buffer, pH 7.0. Potential scan initiated at +650 mV in the negative direction. Potential step increment 4 mV square wave amplitude 25 mV frequency 5 Hz...

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