Crystal crushing

In fact, this qQ ( ) corresponds to the original PSD of the droplets, bubbles, crystals, crushed products, and so on. The limiting values of Eq. (5.8) are expressed as... 

In diagnostic tests crushing of the particles will not always be conclusive. Egg-shell catalysts or other types, zeolites and washcoated monoliths are exceptions. In washcoated monoliths the layer thickness is generally already quite low (<50 (im) and crushing will not yield smaller sizes. Cracking catalysts consist often of zeo-litic crystals of /im dimensions and a binder yielding particles of about 30 /im. If diffusion limitations exist in the zeolitic crystals, crushing will not eliminate these. 

Sodium Hydroxide, 1 N (40.00 g NaOH per 1000 mL) Dissolve about 40 g of sodium hydroxide (NaOH) in about 1000 mL of carbon dioxide-free water. Shake the mixture thoroughly, and allow it to stand overnight in a stoppered bottle. Standardize the clear liquid as follows Transfer about 5 g of primary standard potassium biphthalate [KHCeH4(COO)2], previously dried at 105° for 2 h and accurately weighed, to a flask, and dissolve it in 75 mL of carbon dioxide-free water. If the potassium biphthalate is in the form of large crystals, crush it before drying. To the flask add 2 drops of Phenolphthalein TS, and titrate with the sodium hydroxide solution to a permanent pink color. Calculate the normality. Each 204.2 mg of potassium biphthalate is equivalent to 1 mL of IN Sodium Hydroxide. 

Cost data for blenders and mixers, kneaders, centrifugal separators, crystallizers, crushing and grinding equipment, dust collectors, electrostatic precipitators, and screens are presented in Figs. 14-66 through 14-88. 

For the student interested in crystal growth, potassium aluminum sulfate, also called alum, is a salt available in most pharmacies. It will form single crystals relatively easily from a supersaturated solution. Alum crystals are octahedral in shape and colorless. The related compound, chromium aluminum sulfate dodecahydrate, called chrome alum, forms dark-purple octahedral crystals. Mixing various proportions of supersaturated alum and chrome alum solutions allows the growth of mixed crystals that resemble amethysts in color. (The more alum in the mix, the lighter the purple color of the crystal.) Take the powder patterns of crnshed pnre alum and crushed pure chrome alum, and a mixture of the two compounds. After yon have grown some mixed crystals, crush some and take their powder pattern. Is it different from the two pure materials and from the mixture Explain your observations. 

In spite of the above, it could be argued that a shell effect of absorbed oxygen might result in the increase of Tc. This was shown not to be the case because a small single crystal crushed to powder still showed the same T. ... 

Carefully pour away the liquid from the crystals. Crush crystals into a powder with wooden rod or stick. 

Wash the sample in a solvent (benzene, oxylene, etc.) to remove all hydrocarbons. Rinse the sample in distilled water to remove salt crystals. Crush the sample and mix with enough 37% hydrochloric acid to form a slurry. Dip a platinum wire into the slurry and insert the wire into the flame of a Bunsen burner. Note the color of the flame calcium will emit an orange flame of short duration barium wiU emit a green flame of relatively long duration strontium will emit a crimson flame of relatively long duration. 

Cradled ice and sodium chloride crystals Crushed ice and calcium chloride crystals Acetone or petroleum wqihtha (tee Section 6) chilled in a covered metal beaker with an ice-salt mixture to -12 C then with enough solid carbon dioxide to give the desired temperature. 

Naphthyl Acetate. CHgCOOCi H,. Dissolve 1 g. of pure 2-naphtnol in 5 ml. (r8 mols.) of 10% sodium hydroxide solution as before, add 10 g. of crushed ice, and i-i ml. (1-14 g., 1 5 mols.) of acetic anhydride. Shake the mixture vigorously for about 10-15 minutes the 2-naphthyl acetate separates as colourless crystals. Filter at the pump, wash with water, drain, and dry thoroughly. Yield of crude material, 1-4 g. (theoretical). Recrystallise from petroleum (b.p. 60-80 ), from which, on cooling and scratching, the 2-naphthyl acetate separates as colourless crystals, m.p, 71 yield, 10 g. 

Into a 1-litre beaker, provided with a mechanical stirrer, place 36 - 8 g. (36 ml.) of aniline, 50 g. of sodium bicarbonate and 350 ml. of water cool to 12-15° by the addition of a little crushed ice. Stir the mixture, and introduce 85 g. of powdered, resublimed iodine in portions of 5-6 g, at intervals of 2-3 minutes so that all the iodine is added during 30 minutes. Continue stirring for 20-30 minutes, by which time the colour of the free iodine in the solution has practically disappeared and the reaction is complete. Filter the crude p-iodoaniline with suction on a Buchner funnel, drain as completely as possible, and dry it in the air. Save the filtrate for the recovery of the iodine (1). Place the crude product in a 750 ml. round-bottomed flask fitted with a reflux double surface condenser add 325 ml. of light petroleum, b.p. 60-80°, and heat in a water bath maintained at 75-80°. Shake the flask frequently and after about 15 minutes, slowly decant the clear hot solution into a beaker set in a freezing mixture of ice and salt, and stir constantly. The p-iodoaniline crystallises almost immediately in almost colourless needles filter and dry the crystals in the air. Return the filtrate to the flask for use in a second extraction as before (2). The yield of p-iodoaniline, m.p. 62-63°, is 60 g. 

P-Naphthyl acetate. Dissolve 5 0 g. of p-naphthol in 25 ml. of 10 per cent, sodium hydroxide solution in a 250 ml. reagent bottle, add 60 g. of crushed ice, and 5-7 g. (5 -5 ml.) of acetic anhydride. Shake vigorously for 10-15 minutes the p-naphth acetate separates as colourless crystals. Filter with suction, wash with water, drain and dry in the air. Recrystallise from light petroleum (b.p. 60-80°) or from dilute alcohol. The yield of pure product, m.p. 71°, is 6-5 g. 

Pour the aqueous solution remaining from the ether extraction with stirring into a mixture of 80 ml. of concentrated hydrochloric acid, 80 ml. of water and about 100 g. of crushed ice. Filter the precipitated benzoic acid at the pump, wash it with a little cold water, drain, and recrystallise from boiling water. The yield of benzoic acid (colourless crystals), m.p. 121°, is 18g. 

Meihylamine hydrochloride method. Place 100 g. of 24 per cent, methyl-amine solution (6) in a tared 500 ml. flask and add concentrated hydrochloric acid (about 78 ml.) until the solution is acid to methyl red. Add water to bring the total weight to 250 g., then introduce lSO g. of urea, and boil the solution gently under reflux for two and three-quarter hours, and then vigorously for 15 minutes. Cool the solution to room temperature, dissolve 55 g. of 95 per cent, sodium nitrite in it, and cool to 0°. Prepare a mixture of 300 g. of crushed ice and 50 g. of concentrated sulphuric acid in a 1500 ml. beaker surrounded by a bath of ice and salt, and add the cold methylurea - nitrite solution slowly and with mechanical stirring and at such a rate (about 1 hour) that the temperature does not rise above 0°. It is recommended that the stem of the funnel containii the methylurea - nitrite solution dip below the surface of the acid solution. The nitrosomethylurea rises to the surface as a crystalline foamy precipitate. Filter at once at the pump, and drain well. Stir the crystals into a paste with about 50 ml. of cold water, suck as dry as possible, and dry in a vacuum desiccator to constant weight. The yield is 55 g. (5). 

Sodium anthraquinone-p-sulphonate ( silver salt ). Place 60 g. of fuming sulphuric acid (40-50 per cent. SO3) in a 250 or 500 ml. round-bottomed flask and add 50 g. of dry, finely-powdered anthra-quinone (Section IV,145). Fit an air condenser to the flask and heat the mixture slowly in an oil bath, with occasional shaking, so that at the end of 1 hour the temperature has reached 160°. Allow to cool and pour the warm mixture carefully into a 2 litre beaker containing 500 g. of crushed ice. Boil for about 15 minutes and filter off the unchanged anthraquinone at the pump. Neutralise the hot filtrate with sodium hydroxide and allow to cool, when the greater part of the sodium anthra-quinone-p-sulphonate separates as silvery glistening plates ( silver salt ). Filter these with suction and dry upon filter paper or upon a porous plate. A second crop of crystals may be isolated by concentration of the trate to half the original volume. The yield is 40-45 g. 

---