Gravimetric efficiency

Figure 4.10.1 Current efficiency (gravimetric approach) of electrodeposition experiments in LiCI-KCI-TiCl2.

Gravimetric methods more suitable for general use involve the precipitation of metallic gold from tetrachloraurate solutions by reduction with oxaUc acid, SO2, or hydroquinone. Formaldehyde, hydrazine, ferrous sulfate, and hypophosphorous acid also have been used but are considered less efficient (40). 

The main principles of instrument design are summarized in Table 10.23. In filtration, e.g. for gravimetric analysis, selection of filter material (Table 10.22) requires careful consideration in terms of application, strength, collection efficiency, compatibility with pump, water uptake, etc. Humidity-controlled balance rooms, iTiicrobalances and careful handling techniques may be required. 

Gravimetric efficiency The efficiency of a dust collector to remove a given weight of particulate matter related to the total weight present in the air stream. 

The total lipid content of a sample can be assessed gravimetrically if the lipid is first extracted and then completely dried until a constant weight is recorded. For accurate results, the whole procedure must be designed to minimize the loss of lipids at every stage. This includes using highly efficient extraction and purification techniques under appropriate analytical conditions. 

Figure 2. Gravimetric storage efficiency of composite cylinders (including peripherals)...

The flame must dry, vaporize, and atomize the sample in a reproducible manner with respect to both space and time. Unlike titrimetric and gravimetric analysis, atomic absorption spectrometry is a secondary analytical technique. Concentrations are determined by comparing the absorbance values obtained for samples with those obtained for standards of known determinant concentrations. It is very important, therefore, that samples and standards are always atomized with the same efficiency to produce a cloud of atomic vapour of highly reproducible geometry. If samples and standards behave differently, errors will result. 

Besides the efficiency, the enormous difference in energy density (per mass or volume) deserves to be emphasized. Assuming a height difference of 100 m, the gravimetric energy density is 981 N m kg-1, or 0.27 W h kg-1 in units used in battery... 

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