Cooling tap water

The effect of temperature on reaction rates can be demonstrated with two tablets of effervescent antacid, two cups, and tap water. Into one cup, place a half cup (120 milliliters) of cool tap water from the faucet. In the other cup, place an equal amount of hot tap water from the faucet. Drop one tablet into each cup at the same time. The fizzing action is clearly more vigorous in the hot water than in the cool water. In this case, the higher temperature helps in two ways. It forces more bubbles out of solution (which is the same reason you re cautious about opening a warm can of soda), and it increases the reaction rate because molecules at a higher temperature move around faster, find each other more often, and hit each other harder when they do. This effect and other principles concerning chemical kinetics is the subject of the following discussion. 

PDA (Potato Dextrose Yeast Agar) Wash 250 grams of unpeeled potatoes and slice them 1/8 inch thick. Wash these several times in cool tap water until the water is clear. Drain the slices in a collander and rinse once with distilled water. Cook the potato slices in distilled water until tender. Strain the cooking liquids through a flannel cloth or several layers of cheesecloth and collect the liquid in a flask. Rinse the boiled potatoes... 

Measure this volume plus an additional 0.5 mL in your graduated cylinder. Record the volume and the actual molarity of this NaOH solution in TABLE 21.lA. Put it into another beaker. Measure the temperatures of both the HCl and the NaOH solutions, and adjust these temperatures using cool tap water surrounding the containers so that they are the same and preferably a few degrees below room temperature. Be careful to rinse and wipe your thermometer clean before shifting from acid to base or vice versa. Record these temperatures in TABLE 21.lA. Add 2 drops of phenolphthalein to your HCl solution. 

The separated buttermilk is drained. Its milk fat content should be as low as possible which is mainly influenced by the way of physical cream ripening. Sweet buttermilk contains more milk fat (0.3-0.6%) than sour buttermilk (0.2-0.3%). The butter granules are washed with cool tap water to reduce the buttermilk solids content. This step is omitted in cases where buttermilk drainage is sufficient. The process of buttermilk and wash water removal is controlled in such a way that a low residual water content (about 13%) is obtained, so that the final water content can be adjusted to 16% by controlled addition of flavour concentrates/cooking salt solution/water. Addition of sour flavour concentrates allows the... 

The coating panels under test were cut into a 10 x lOmm piece by a shear cutter to fit the sample stage of the SPM. Before the test, the samples were washed in an ultrasonic bath with a mild solvent-free detergent, rinsed in a stream of cool tap water, gently dried with soft tissue, and then were blown dry with high pressure nitrogen gas. 

Nitric acid is prepared in the laboratory by distilling equal weights of potassium nitrate and concentrated sulphuric acid using an air condenser, the stem of which dips into a flask cooled by tap water. The reaction is ... 

Concurrently with the preparation of the phenyldiazonium chloride solution, prepare a cold suspension of sodium arsenite. Place 250 ml. of water in a 3-htre round-bottomed flask equipped with a mechanical stirrer. Heat the water to boding, add 125 g. of anhydrous sodium carbonate, and, as soon as the carbonate has dissolved, introduce 62 5 g. of pure arsenious oxide and 3 g. of crystallised copper sulphate with stirring. When all the solids have dissolved, cool the solution with stirring under a stream of tap water until the temperature has fallen to 15°. 

Hydrolysis of benzyl cyanide to phenylacetamide. In a 1500 ml. three-necked flask, provided with a thermometer, reflux condenser and efficient mechanical stirrer, place 100 g. (98 ml.) of benzyl]cyanide and 400 ml. of concentrated hydrochloric acid. Immerse the flask in a water bath at 40°. and stir the mixture vigorously the benzyl cyanide passes into solution within 20-40 minutes and the temperature of the reaction mixture rises to about 50°, Continue the stirring for an additional 20-30 minutes after the mixture is homogeneous. Replace the warm water in the bath by tap water at 15°, replace the thermometer by a dropping funnel charged with 400 ml. of cold distilled water, and add the latter with stirring crystals commence to separate after about 50-75 ml. have been introduced. When all the water has been run in, cool the mixture externally with ice water for 30 minutes (1), and collect the crude phenylacetamide by filtration at the pump. Remove traces of phenylacetic acid by stirring the wet sohd for about 30 minutes with two 50 ml. portions of cold water dry the crystals at 50-80°. The yield of phenylacetamide, m.p. 154-155°, is 95 g. RecrystaUisation from benzene or rectified spirit raises the m.p. to 156°. 

The suspension of phenylacetamide may be further hydrolysed to phenylacetic acid by refluxing with stirring until the solid dissolves. The mixture becomes turbid after 30 minutes and the product begins to separate as an oil refluxing is continued for 6 hours, the mixture is cooled first with tap water and then by an ice-water bath for about 4 hours. The crude phenylacetic acid is filtered at the pump, washed with two 50 ml. portions of cold water, and dried in a desiccator. The resulting crude acid melts at 69- 70° it may be purified by recrystallisation from light p>etroleum (b.p. 40-60°) or, better, by vacuum distillation. 

The cloudiness of ordinary ice cubes is caused by thousands of tiny air bubbles. Air dissolves in water, and tap water at 10°C can - and usually does - contain 0.0030 wt% of air. In order to follow what this air does when we make an ice cube, we need to look at the phase diagram for the HjO-air system (Fig. 4.9). As we cool our liquid solution of water -i- air the first change takes place at about -0.002°C when the composition line hits the liquidus line. At this temperature ice crystals will begin to form and, as the temperature is lowered still further, they will grow. By the time we reach the eutectic three-phase horizontal at -0.0024°C we will have 20 wt% ice (called primary ice) in our two-phase mixture, leaving 80 wt% liquid (Fig. 4.9). This liquid will contain the maximum possible amount of dissolved air (0.0038 wt%). As latent heat of freezing is removed at -0.0024°C the three-phase eutectic reaction of... 

Fluoro-l 13,17ot-Dihydroxy-21-Acetoxy-1,4-Pregnadiene-3,20-Dione A medium consisting of 1% dextrose hydrate, 2% cornsteep liquor of 60% solids and Kalamazoo tap water was adjusted to pH 4.9 with sodium hydroxide. The medium was steam sterilized at 15 pounds pressure for 30 minutes, cooled, and then inoculated with a 24-hour growth, from spores, of Septomyxa affinis, ATCC 6737. The medium was agitated, sparged with sterile air at the rate of one-tenth volume of air per volume of medium per minute. At the end of 24 hours of fermentation at room temperature, the pH was about 7.4. 

To 19 8 of well-agitated distilled water plus 18 g of ditertiary-butyl-ppinene oxide that was about half racemic, half d-form. The temperature was maintained at 30°C to 50°C, first with ice bath cooling and then with tap water cooling. The addition of the pinene oxide required 1 h hours. After the addition was complete and the exothermic reaction was about over, the mixture was stirred for 1 h hours at about 30°C, and then centrifuged to separate the crude sobrerol from the liquid phase consisting of oil and water. 

Procedure. To obtain experience in the method, the purity of analytical-grade potassium chlorate may be determined. Prepare a 0.02M potassium chlorate solution. Into a 250 mL conical flask, place 25.0 mL of the potassium chlorate solution, 25.0mL of 0.2M ammonium iron(II) sulphate solution in 2M sulphuric acid and add cautiously 12 mL concentrated sulphuric acid. Heat the mixture to boiling (in order to ensure completion of the reduction), and cool to room temperature by placing the flask in running tap water. Add 20 mL 1 1 water/phosphoric(V) acid, followed by 0.5 mL sodium diphenyl-amine-sulphonate indicator. Titrate the excess Fe2+ ion with standard 0.02M potassium dichromate to a first tinge of purple coloration which remains on stirring. 

Close the hinged cap on the dropping bottle and immediately remove the bottle from the hot water. Cool the bottle by immersing it in another 1000-mL beaker containing tap water. 

The volume of water in the bottle is equal to the change in volume of the air as it cooled from the temperature of boiling water to the temperature of tap water. Use a graduated cylinder to accurately measure the volume of the water in the bottle. 

Obtain a clean dropping bottle. Repeat Part A of this activity, only cool the dropping bottle in the boiling water this time by immersing it in a beaker of ice water instead of tap water. 

Synthetic Method 1 6-(dimethylamino)-3-(N-acetyl-N-methylamino)-10-acetylphenothiazine 8a (procedure from US. Patent 4,652,643).5 A mixture of 9.0g of 6-(dimethylamino)-3-(methylamino)phenothiazin-5-ium chloride (Azure B), 150.0ml of acetic anhydride, and lO.Og of zinc dust was maintained at reflux temperature for approximately 4 hs. After the reaction mixture was cooled to ambient temperature, it was poured into ice water with stirring and 300ml of toluene was added. After stirring for approximately 30 min the toluene layer was separated and washed twice, once with tap water and once with saturated aqueous sodium chloride solution. The toluene was then distilled off at reduced pressure. The residue which remained was dissolved in ethyl acetate and separated into various components by subjecting the solution to column chromatography using silica gel as substrate. Elution with ethyl acetate yielded a white-colored solid. 

The preparation may be carried out in a more concentrated solution (1000 cc. of alcohol) with the same yield, but an inferior product is obtained. If this is done, it is best to stir for fifteen minutes at 50° after all the cyanide has been added and then cool in tap water. Since the product separates as an oil from a solution of this concentration, it is best to inoculate with a crystal of the nitrile. 

Ordinary tap water flowing through the discharge-tube jacket has been found to provide adequate cooling. The tap-water temperature has varied from 5 to 18° with no significant change in results. 

During the addition the temperature is maintained at 28-31° (Note 3) by cooling the flask, as needed, by a stream of tap water. The solution is allowed to stand overnight and is then treated with 800 ml. of water to dissolve the precipitated quinoline hydrochloride (Note 4). The mixture is shaken well in a separatory funnel the organic layer is separated and washed with two 200-ml. portions of water and three or four 200-ml. portions of 5% hydrochloric acid. After the extract has dried over anhydrous magnesium sulfate for 5 hours, the solvent is removed by distillation, a water aspirator being used to remove the last portions of the methylene dichloride. Distillation of the residue from a 1-1. Claisen flask by means of an air bath maintained at 125-135° gives 460-495 g. (71-76%) (Note 5) of a colorless oil, b.p. 74-78° (0.5 mm.), 24d 1.4832. This product is sufficiently pure for use in the preparation below. 

One of the simplest ways to tell at a glance if our tap water contains much Ca2+ - we say it is hard - is to look at the bath after letting out the water. Surfactants form micelles with the calcium di-cation at temperatures above 7k, i.e. in a hot bath. But after cooling to a temperature of about 20 °C, the micelles precipitate to yield hydrated crystals - which we observe as a ring of scum along the waterline. 

B) a-Bromo-fi-methoxypropionic Acid.—Eight hundred grams of the bromo ester and 11. of 0.5 N sodium hydroxide are placed in a 5-I. three-necked flask equipped with an efficient stirrer and a separatory funnel, and cooled with running tap water. The stirrer is started, and 800 cc. of 5 N sodium hydroxide is added during the course of two hours. After the addition is complete, the solution is stirred for one hour and then neutralized with an equivalent quantity of sulfuric acid (Note n). The neutralized solution is extracted once with a i-l. portion, and three times with 500-cc. portions, of ether. The ether extracts are combined, washed once with a cold saturated solution of sodium sulfate, and dried over anhydrous sodium sulfate the ether is removed by distillation (Note 12). There remains 700-750 g. of crude bromo acid which is used without purification in the preparation of serine (Note 13). 

The temperature may be controlled by passing tap water through an 8-mm. glass cooling coil mounted in the beaker. The bromination proceeds rapidly at 45-55°, rather slowly at 35-40°, and practically ceases below 30°. 

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