Pestle

When the adsorbent has been introduced into the tube, the latter is fitted into a filter flask (see Fig. 77, 46, 2) to which a pump is attached the pump is run slowly and the column is again pressed down gently with the wooden pestle. The circumference of the upper surface is gently and uniformly tapped, especially where it is in contact with the glass surface, for about one minute air bubbles and channels are thus avoided when the solution is poured in. Some workers place a loose plug of cotton wool or a circle of filter paper at the top of the column in order to protect the solid from disturbance when the liquid is introduced. 

The residual reagent must be carefully destroyed. That remaining in the mortar is slowly dropped into about 2 litres of water in a large beaker. The solid adhering to the pestle should be scraped off and added gradually to excess of water. 

In this experiment students measure the length of a pestle using a wooden meter stick, a stainless-steel ruler, and a vernier caliper. The data collected in this experiment provide an opportunity to discuss significant figures and sources of error. Statistical analysis includes the Q-test, f-test, and F-test. 

Crushing and grinding uses mechanical force to break larger particles into smaller ones. A variety of tools are used depending on the particle s size and hardness. Large particles are crushed using jaw crushers capable of reducing particles to diameters of a few millimeters. Ball mills, disk mills, and mortars and pestles are used to further reduce particle size. 

Because of the risk of lead poisoning, the exposure of children to lead-based paint is a significant public health concern. The first step in the quantitative analysis of lead in dried paint chips is to dissolve the sample. Corl evaluated several dissolution techniques. " In this study, samples of paint were collected and pulverized with a Pyrex mortar and pestle. Replicate portions of the powdered paint were then taken for analysis. Results for an unknown paint sample and for a standard reference material, in which dissolution was accomplished by a 4-6-h digestion with HNO3 on a hot plate, are shown in the following table. 

Samples of animal bones weighing approximately 3 g are ashed at 600 °C until the entire bone is ash-white. Samples are then crushed in a mortar and pestle. A portion of the sample is digested in HCl and diluted to a known volume. The concentrations of zinc and strontium are determined by atomic absorption. The analysis for strontium illustrates the use of a protecting agent as La(N03)3 is added to prevent an interference due to the formation of refractory strontium phosphate. 

Several aspirin tablets are ground to a fine powder in a mortar and pestle. A 0.1013-g portion of the powder is placed in a 1-L volumetric flask and diluted to volume with distilled water. A portion of this solution is filtered to remove insoluble binders, and a 10.00-mL aliquot transferred to a 100-mL volumetric flask containing 2.00 ml of 4 M NaOH. After diluting to volume the fluorescence of the resulting solution is found to be 8.69. What is the %w/w acetylsalicylic acid in the aspirin tablets ... 

A MIXTURE of 120 g. (3 moles) of sodamide (Note i) and 200 cc. of purified mineral oil (Note 2) is ground together in a mortar until the amide is finely pulverized (Note 3). This suspension is transferred to a 2-I. round-bottom, three-necked flask fitted with a reflux condenser holding a calcium chloride tube, a 500-cc. separatory funnel, and an efficient mechanical stirrer through a mercury seal. The mortar and pestle are rinsed with an additional 250 cc. of the oil which is then added to the reaction flask. This is heated in an oil bath maintained at 160-165, the stirrer is started and 203 g. (i mole) of cyclohexylbromopropene (p. 20) is dropped in during one and one-half hours. Ammonia is evolved and this is allowed to pass through the condenser and is collected in water. 

The technique of trituration is frequently useful. The organic product is stripped of solvent and the oily residue is placed in a mortar and covered with a layer of a solvent in which it is only slightly soluble. The mass is ground with a pestle mixing in the solvent as thoroughly as possible. In favorable cases, the solvent removes traces of impurities that may be inhibiting crystallization, and grinding action induces crystallization. 

Mdrser, m. mortar (the vessel and the cannon), -keule, /. pestle, -probe, /. morfar test, -stdssel, m. pestle. 

Stampfe,/. stamp, stamper, pestle, punch, rammer, ram, hammer. 

Stempel, m. stamp stamper, die, punch, pestle piston brand, mark pistil post, prop, -farbe, /. stamping ink. -kissen, n. stamp-(ing) pad, -marke, /. stamp. 

Stossel, m. pestle stamper, rammer tappet, stossempfindlich, a. sensitive to shock, stossen, v.t. push, thrust, hit, knock, ram pound, bray, pulverize join slot. — v.t. thrust, dash, hit (at, against, or upon) (of boiling liquids) bump, knock recoil. Stosser, m. pestle rammer, pounder, knocker. Stossfitnger, m. pressure equalizer, shock absorber. 

Procedure (iodometric method). Weigh out accurately about 5.0 g of the bleaching powder into a clean glass mortar. Add a little water, and rub the mixture to a smooth paste. Add a little more water, triturate with the pestle, allow the mixture to settle, and pour off the milky liquid into a 500 mL graduated flask. Grind the residue with a little more water, and repeat the operation until the whole of the sample has been transferred to the flask either in solution or in a state of very fine suspension, and the mortar washed quite clean. The flask is then filled to the mark with distilled water, well shaken, and 50.0 mL of the turbid liquid immediately withdrawn with a pipette. This is transferred to a 250 mL conical flask, 25 mL of water added, followed by 2 g of iodate-free potassium iodide (or 20 mL of a 10 per cent solution) and 10 mL of glacial acetic acid. Titrate the liberated iodine with standard 0.1M sodium thiosulphate. 

In theory, increased quantities of the organic compound finely ground with constant quantities of potassium bromide should give infrared spectra of increasing intensity. However, good quantitative results by this direct procedure are difficult to obtain due to problems associated with the non-quantitative transfer of powder from the small ball-mill grinder (or pestle and mortar) into the compression die. These are only partially overcome by using a micrometer to measure the final disc thickness. 

Acetone powder (1.5 g) was extracted 4 times with 0.1 M sodium borate buffer (pH 7.6) at 4°C, homogenizing each time with a glass grinder equipped with a Teflon pestle. The first extraction was carried out with 80 ml of the buffer, followed by 3 times with 70 ml each of the buffer. Each homogenate was centrifuged at 16,000 g for 5 min. All supernatants were combined. 

Figure 9. Procedure for the preparation of the test electrode for aqueous electrolytes (9 mol L 1 KOH or ZnCl2 solution). (1) the sample is mixed by shaking in a plastic container 20 mm (diam.) x 40 mm (height) (2) the mixture is made into a thin film by grinding with a pestle in a ceramic mortar (3) the metal screen is prepared (4) the three layers (A, B, C) are pressed between the steel blocks.

This must be ground into a fine powder with a mortar and pestle immediately prior to use. 

The absence of water in the lithium bromide is of great importance. Traces of wrater lower the yield of product by 10-20%. LiBr-2 H20 (purchased from E. Merck Company, Inc., Darmstadt or City Chemical Corporation) was dissolved three times in anhydrous acetonitrile-benzene (1 1), and the solvents removed each time on a rotary evaporator. The lithium bromide was dried under high vacuum at 100° for 1 hour, ground to a fine powder with a mortar and pestle while still warm, and again dried at 100°, as above, for 3 hours. 

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