BaCl

BaCl IH O 244.28 Dissolve clear crystals of the salt in distilled water. Standardize against K2SO4 or Na2S04. 

The worked out soi ption-photometric method of NIS determination calls preliminary sorption concentration of NIS microamounts from aqueous solutions on silica L5/40. The concentrate obtained is put in a solution with precise concentration of bromthymol-blue (BTB) anionic dye and BaCl, excess. As a result the ionic associate 1 1 is formed and is kept comparatively strongly on a surface. The BTB excess remains in an aqueous phase and it is easy to determinate it photometrically. The linear dependence of optical density of BTB solutions after soi ption on NIS concentration in an interval ITO - 2,5T0 M is observed. The indirect way of the given method is caused by the fact the calibration plot does not come from a zero point of coordinates, and NIS zero concentration corresponds to initial BTB concentration in a solution. 

Because of count rate performance and peak-to-bacl round, WDS is preferable to EDS for mapping, particularly for minor and trace constituents. 

One should compare capabilities to the electron beam X-ray emission methods of Chapter 3. The major difference is the higher lateral resolution with electron beams and the associated mapping capabilides. Another difference is the shorter probing depth possible with electrons, except when compared to the specialized TXRF method. Comparing electron-beam EDS to X-ray/particle EDS or electron-beam WDS to X-ray/particle WDS, the electron beams have poorer detection limits because of the greater X-ray bacl ound associated with electron... 

The basic bacl round and understanding of binary distillation applies to a large measure in multicomponent problems. Reference should be made to Figure 8-1 for the symbols. 

Demeton-S-methyl sulfone (h/ f 0-5), dimethoate (h/ f 5-10), demeton-S-metlq (h/ f 20-25), triazophos (h/ f 40-45), azinphos-methyl (h/ f 40-45), azinphos-etiq (h/ f 50-55), malathion (h/ f 60-65), parathion-methyl (h/ f 75-80) and parathion ethyl (h/ f 80-85) yielded yellow to brown chromatogram zones on a light brown bacl ground, with thiophosphate insectiddes with P=S double bonds appearing as brow zones and those with single P —S bonds as yellow zones. 

Since they react in a 1 1 mole ratio, the BaCl, is obviously in limiting quantity. 

Calculate the number of grams of BaS04 that can be prepared by treating 3.00 L of 0.253 M BaCL with excess Na2S04. 

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