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Sodium carbonate stop baths

Mix 30 g. (38 ml.) of iaopropyl alcohol with 450 g. (265 ml.) of constant boiling point hydriodic acid (57 per cent.) (Section 11,49,2) in a 500 ml. distilling flask, attach a condenser for downward distillation, and distil slowly (1-2 drops per second) from an air bath (compare Fig. II, 5, 3). When about half the liquid has passed over, stop the distillation. Separate the lower layer of crude iodide (80 g.). Redistil the aqueous layer and thus recover a further 5 g. of iodide from the flrst quarter of the distillate (1). Wash the combined iodides with an equal volume of concentrated hydrochloric acid, then, successively, with water, 5 per cent, sodium carbonate solution, and water. Dry with anhydrous calcium chloride and distil. The isopropyl iodide distils constantly at 89°. [Pg.285]

In a 5-I. round-bottomed flask, 500 g. (5.3 moles) of chloro-acetic acid (Note 1) is dissolved in 700 cc. of water. The solution is warmed to 50°, neutralized with 290 g. (2.7 moles) of anhydrous sodium carbonate, and again cooled to room temperature. Meanwhile, 294 g. (6.0 moles) of sodium cyanide (97 per cent) is dissolved in 750 cc. of water warmed to 55°, the solution is cooled to room temperature, and then added to the sodium chloroacetate solution, with rapid mixing of the two solutions and cooling under the water tap. When the solutions are completely mixed, the cooling is stopped and the temperature allowed to rise. When it reaches 95° the solution is cooled by adding 200 cc. of ice water, and this is repeated, if necessary, until the temperature no longer rises (Note 2). The solution is then heated on the steam bath for one hour to ensure completion of the reaction. [Pg.50]

Balanced Alkali is a proprietary chemical of Eastman Kodak, and until recently it was known as Kodalk . Balanced Alkali is more alkaline than borax and more easily soluble, but less alkaline than carbonate. As Balanced Alkali contains no free carbonate, there is no danger of carbonic gas bubbles being formed when an acid stop bath is used (see the next section, Moderate Alkalis). Balanced Alkali can be substituted for carbonate (Conversion Tables Alkali Substitutions), and for almost all purposes it is identical to sodium metaborate. [Pg.24]

Notes Sodium carbonate releases a gas when added to an acid stop bath or an acid fixing bath this gas may cause pinholes, or blistering, to develop in film emulsions. [Pg.192]

Procedure For each sample or blank, pipet 2.0 mL of the Substrate solution into a 25- x 150-mm test tube, and equilibrate in a water bath maintained at 37.0° 0.1° for approximately 10 min. At zero time, rapidly pipet 0.5 mL of the Test Preparation (or 0.5 mL of water as a blank) into the equilibrated substrate, mix by brief (Is) vortex, and immediately return the tubes to the water bath. After exactly 15 min of incubation, rapidly add 2.5 mL of 10% sodium carbonate solution, and vortex the tube to stop the enzyme reaction. Dilute the samples and blanks to 25.0 mL by adding 20.0 mL of water, and thoroughly mix. Determine the absorbance of... [Pg.913]


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