Sampling of solids

Ultramicrotomy is sometimes also used to produce thin samples of solid materials, such as metals [13] which are, however, preferentially prepared by chemical- or ion-etching (see [1]) and focused ion beam (FIB) teclmiques [14]. 

The quantity of gas taken up hy a sample of solid is proportional to the mass m of the sample, and it depends also on the temperature T, the pressure p of the vapour, and the nature of both the solid and the gas. If n is the quantity of gas adsorbed expressed in moles per gram of solid,... 

When it is desired to evaluate the specific surfaces of a set of closely related samples of solid, however, only one of the samples needs to be calibrated against nitrogen (or argon), provided that all the isotherms of the alternative adsorptive can be shown to have indentical shape. A simple device for testing this identity, by use of the a,-plot, is described in Section 2.13 by means of the a,-plot it is also possible to proceed directly to calculation of the specific surface without having to assign a value to or to evaluate the BET monolayer capacity, of the alternative adsorptive. 

The pH of a 1% solution of pure sodium tripolyphosphate is 9.9 and that of commercial samples may vary between 9.5 and 10.1. The pH of a given sample of solid STP drops slowly with age because of water adsorption and partial reversion to orthophosphate and pyrophosphate. The pH of solutions varies with concentration because the sodium ion is bound in the complex form NaP O o higher concentrations maximum pH is reached at between 1—2% solution. 

Harrison Coopor/ Ph D / Harrison R. Cooper Systems, Inc., Salt Lake City, Utah. (Sampling of Solids and Slurrie.s)... 

Example 7 Cross-Belt Sampling of Solids from Conveyors... 

Direct sampling of solids may be carried out using laser ablation. In this technique a high-power laser, usually a pulsed Nd-YAG laser, is used to vaporize the solid, which is then swept into the plasma for ionization. Besides not requiring dissolution or other chemistry to be performed on the sample, laser ablation ICPMS (LA-ICPMS) allows spatial resolution of 20-50 pm. Depth resolution is 1-10 pm per pulse. This aspect gives LA-ICPMS unique dit nostic capabilities for geologic samples, surface features, and other inhomogeneous samples. In addition minimal, or no, sample preparation is required. 

Another method devised for direct sampling of solids involves direct insertion of the sample into the plasma. In this procedure the sample is delivered through the central tube of the torch. The sample may be premixed with graphite powder. 

Even the sampling of solids must not be casually undertaken, and the operator should always use a face mask as a protection until it is established that the powdered material is not hazardous. 

FIGURE 7.7 A tiny sample of solid carbon monoxide consisting of foui molecules. Each box represents a different arrangement of the four molecules. When there is only one way of arranging the four molecules so that they all point in one direction (as in the top left image), the entropy of the solid is zero. When all sixteen ways of arranging four CO molecules arc accessible, the entropy of the solid is greater than zero. 

C02-0037. Iodine is an element whose molecules can move directly from the solid to the gas phase. A sample of solid iodine in a stoppered flask stood undisturbed for several years. As the photo shows, crystals of solid iodine grew on the sides of the flask. Use the principle of dynamic equilibrium to explain at the molecular level what happened. Include an observation about the color of the atmosphere inside the flask. 

C03-0152. Aluminum sulfate is used in the manufacture of paper and in the water purification industry. In the solid state, aluminum sulfate is a hydrate. The formula is AI2 (804)3 18 H2 O. (a) How many grams of sulfiar are there in 0.570 moles of solid aluminum sulfate (b) How many water molecules are there in a 5.1-g sample of solid aluminum sulfate (c) How many moles of sulfate ions are there in a sample of solid aluminum sulfate that contains 12.5 moles of oxygen atoms (d) An aqueous solution of aluminum sulfate contains 1.25% by mass aluminum and has a density of 1.05 g/mL. What is the molarity of aluminum ions in the solution ... 

Sampling of solid material often produces much more material than can be submitted to the laboratory for analysis. Reducing a large composite sample to a suitably sized laboratory sample often involves the following three steps ... 

Samples of groundwater were obtained from piezometers installed at various locations throughout the tailings. Groundwater was retrieved using a baler. Pore water was squeezed from samples of solid tailings. All water samples were analysed for cations, anions, Eh and pH. 

The devices used for sampling of solid samples (sludge, sediment, and soil) are usually grab samplers or corers. Box corers or multicorers can be employed if more detailed information on the spatial distribution of the analytes is needed. The samples are stored in the dark at 4 °C or more commonly at -20 °C, preferably in glass containers [53]. Very often, solid samples are also dried or lyophilized prior to storage. 

A student obtained a 24-well plate and placed samples of solid metals into solutions of various metallic ions. The results are presented in Table 1 below ... 

Except for the moon and the planet Mars, no extraterrestrial body has had pieces of its mass directly examined by scientists in an earthly laboratory. This means that there has been no laboratory sample preparation scheme performed on samples of solid matter from any of the other planets, their moons, comets, or asteroids. And yet we read repeatedly about how scientists have been able to surmise the... 

Sampling of solid materials are comparatively more difficult than other materials because of the following three reasons, namely ... 

Sampling of solids can be best accomplished by adopting the following procedures ... 

Give a plausible reason for the irreproducibility of substitution reactions of Fe (CN)5H20 . The ion had been prepared in solution from a sample of solid Na2Fe(CN)5H20 which had not been overly purified. Addition of a small amount of Brj slowed down the substitution reaction and gave more consistent data. 

Removal of metals by immobilized ligands frequently involves a choice of two techniques, a batch method or column chromatography. The batch method can be faster when samples are taken from the supernatant for replicate analyses. This method also can establish when equilibrium (or stasis) has been established. One flaw is that the sample of solid may not be... 

Figure 2. Schematic of the processing of sludge samples to produce uniform samples of solids.

Nitrite (N02) can be determined by oxidation with excess Ce4+, followed by back titration of the unreacted Ce4+. A 4.030-g sample of solid containing only NaN02 (FM 68.995) and NaN03 was dissolved in 500.0 mL. A 25.00-mL sample of this solution was treated with 50.00 mL of 0.118 6 M Ce4+ in strong acid for 5 min, and the excess Ce4+ was back-titrated with 31.13 mL of 0.042 89 M ferrous ammonium sulfate. 

We subject a sample of solid polymer material to a sudden deformation process y0, with an elastical stress o0 = Gy0 (G shear modules). The original strain gives rise to an increase of the molecular valency angles and the intermolecular distances. From these molecular deformations an elastic molecular potential A0 arises which in turn causes molecular displacements. These prevail in the direction of the original strain, decreasing the elastic potential A in that neighborhood. We can calculate... 

FIGURE 7.5 A tiny sample of solid carbon monoxide consisting of four molecules. When there is only one way of arranging the molecules so that all the molecules point in one direction, the entropy of the solid is 0. 

One important form of spectroscopy has developed directly from the photoelectric experiments described above. By making the electrons pass between two slits, with a deflecting electric field in between, their complete energy distribution can be measured, rather than just the maximum emitted energy as in Fig. 1.10. This is known as photoelectron spectroscopy, and may be performed on gases or solids, with radiation in the UV or X-ray ranges of the spectrum. Figure 1.11 shows the type of apparatus used, and the spectrum obtained from a sample of solid CdO. A series of peaks is found, and the interpretation based on Einstein s theory is also shown. 

In the first series of experiments, six samples of solid, chosen to cover a wide fluctuation of gibberellic quality, were assayed by three operators in sextuplicate on six occasions during 3 days. The results indicated a standard error of 1% over the whole series, slightly better on the purer samples and slightly worse on material of poor quality. 

Figure 11.2. Rates of desorption of gases from polystyrene pellets and granules. Samples of solid polystyrene were saturated with gas at high pressure prior to measurement. The sample weights are measured continuously as gas desorbs from the sample at room temperature and atmospheric pressure. The label pellets refers to the 1/8 in x 1/8 in diameter polystyrene pellets received from the manufacturer, while granules refers to pellets ground to approximately 14 mesh size. Data from Kwag (1998).

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