Barium ionization

Adding an excess of a more easily ionized element to all standards and samples eliminates ionization interference. This addition creates a large number of free electrons in the flame. The free electrons are captured by the analyte ions, converting them back to atoms. The result is to suppress the ionization of the analyte. Elements often added as ionization suppressants are potassium, rubidium, and cesium. For example, in the AAS determination of sodium, it is common to add a large excess of potassium to all samples and standards. Potassium is more easily ionized than sodium. The potassium ionizes preferentially and the free electrons from the ionization of potassium suppress the ionization of sodium. The detection limit of the sodium determination thereby decreases. The ionization suppression agent, also called an ionization buffer, must be added to all samples, standards, and blanks at the same concentration for accurate results. An example of the use of ionization suppression is shown in Fig. 6.20. Absorbance at a barium resonance line (atomic absorption) and absorbance at a barium ion line (by barium ions in the flame) are plotted as a function of potassium added to the solution. As the potassium concentration increases, barium ionization is suppressed the barium stays as barium atoms. This results in increased atomic absorption at the resonance line and a corresponding decrease in absorbance at the ion line. The trends in absorbance at the atom and ion lines very clearly show that barium ion formation is suppressed by the addition of 1000 ppm of the more easily ionized potassium. 

Figure 6.20 The suppression of barium ionization in a flame atomizer by addition of the more easily ionized element potassium. [From Beaty and Kerber, used with permission of PerkinEbner, Inc. (www.perkinebner.com).]...

Figure 6.20 The suppression of barium Ionization in a flame atomizer by addition of the more easily ionized...

Hydrolysis of metal-organic solutions Example. Ba(OC3H7)2 + Ti(OC5Hu)4 + H2O — BaTiOs (Barium isopropoxide and Titanium tertiary amyloxide are refluxed in isopropanol and then hydrolyzed with de-ionized water to produce a sol-gel. ... 

Salt formation. The resin acids have a low acid strength. The pa s (ionization constants) values of resin acids are difficult to obtain, and values of 6.4 and 5.7 have been reported [23] for abietic and dehydroabietic acids, respectively. Resin acids form salts with sodium and aluminium. These salts can be used in detergents because of micelle formation at low concentrations. Other metal salts (resinates) of magnesium, barium, calcium, lead, zinc and cobalt are used in inks and adhesive formulations. These resinates are prepared by precipitation (addition of the heavy metal salt to a solution of sodium resinate) or fusion (rosin is fused with the heavy metal compound). 

On the basis of your knowledge of periodicity, place each of the following sets of elements in order of decreasing ionization energy. Explain your choices, (a) Selenium, oxygen, tellurium (b) gold, tantalum, osmium (c) lead, barium, cesium. 

Desmids, strontium and barium sulfate biomin-eralization, 36 170-171 Desorption ionization techniques, 28 6-7, 21 Desulfoferrodoxin (Dfx), in sulfate-reducing bacteria, 47 366-367 Desulfofnscidin, 47 387 Desulforedoxin, 47 362-363, 424, 425, 448 Desulforubidin, 47 387 Desulfovibrio... 

Barium is almost as powerful a reducing agent as is Cs. but La is somewhat less so. The appropriate sums of the ionization energies and the enthalpies of atomization compete well with the enthalpies of hydration for Cs and Ba, but the enthalpy of hydration of the La 1"1" ion is not sufficiently negative to outweigh the large third ionization energy. 

Resonance-ionization mass-spectrometry is still in the development stage in terms of its application to cosmochemistry. The Charisma instrument, which is operated by Argonne National Laboratories, uses multiple lasers to resonantly ionize only the elements of interest, which are then analyzed with a time-of-flight mass spectrometer. The Charisma instrument has made isotopic measurements of molybdenum, zirconium, strontium, ruthenium, barium and other elements in presolar grains. These measurements are made possible by the high ionization efficiency of the RIMS technique and its ability to completely eliminate isobaric interferences. Work is now underway to build a RIMS instrument that can be operated by an individual investigator in a university laboratory. If this succeeds, RIMS will play an increasing role in analysis of extraterrestrial materials. 

In general, ionization potentials decrease as we descend the periodic table within a given group. This is as we might expect, since the atoms increase in size. The first IP is 899 kJ mol-1 for beryllium and falls to 503 kJ mol-1 for barium, down Group 2. As we cross the periodic table from left to right, IP values tend to rise ... 

Hydrofluoric acid like water is an associated liquid, and even the gas, as we shall soon see, is associated. It has the power of uniting with fluorides. It also seems to be an ionizing solvent for a soln. of potassium fluoride in liquid hydrogen fluoride is an excellent conductor it also possesses marked solvent powers. According to E. C. Franklin,7 the liquid readily dissolves potassium fluoride, ehloride, and sulphate sodium fluoride, bromide, nitrate, chlorate, and bromate acetamide and urea. The solvent action is not so marked with barium fluoride, cupric chloride, and silver cyanide while calcium and lead fluorides copper sulphate and nitrate ferric chloride, mercuric oxide, and magnesium metal, are virtually insoluble in this menstruum. Glass also is not affected by the liquid if moisture be absent. The liquid scarcely acts on most of the metals or non-metals at ordinary temp., though it does act on the alkali metals at ordinary temp., much the same as does water, with the simultaneous production of flame. 

Muller first noted field desorption for layers of barium on tungsten (1). He concluded correctly that tunneling could hardly be responsible for the ionization of heavy particles and assumed that the potential curve for the ad-atom substrate complex was deformed to the point where activated desorption over the barrier could take place. This view was supported by the fact that he found that the field necessary for the desorption of thorium was quite temperature dependent, changing from the (remarkably low) value of 6.7 X 10 v./cm. at room temperature to 3.5 X 10 v./cm. at 1500°K (1). Similar results were found by him for barium... 

An s-block element has a low ionization energy, which means its outermost electrons can be lost easily. A Group 1 element is likely to form +1 ions, such as Li+, Na+, and K+. Group 2 elements similarly form +2 ions, such as Mg2+, Ca2+, and Ba2+. An s-block element is likely to be a reactive metal with all the features that the name metal implies (Fig. 1.48, Table 1.4). Because ionization energies are lowest at the bottom of each group, and the elements there lose their valence electrons most easily, the heavy elements cesium and barium react most vigorously of all s-block elements. They have to be kept stored out of contact with air and water. The alkali metals have few direct uses as materials but are enormously important as compounds. 

Place the following in order of increasing first ionization energy magnesium, calcium, barium. 

P. 0. Ray and N. R. Dhar also measured the electrical conductivities of soln. of the three nitrites and P. C. Ray and 8. C. Mukherjee observed that the degrees of ionization of soln. of calcium nitrite at dilutions t =28-0 and 19-4 litres are respectively 0-84 and 0-82 for strontium nitrite at dilutions v—22-0 and 21-0 litres, 0-84 in both cases and for barium nitrite for c=21-0 and 31-4 litres, respectively 0-84 and 0-86. 

Rai et al. 1984). Barium is transported in the atmosphere, surface waters, soil runoff, and groundwater. In surface waters and soils, barium may ionize and form various salts depending on the pH and the availability of anions (Bates 1988 Bodek et al. 1988 Bowen 1966 Kabata- Pendias and Pendias 1984 Lagas et al. 1984). Additional information on the transport and transformation of barium in the atmosphere would be useful in developing a more complete understanding of the environmental fate of barium compounds. 

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