Granulated Zinc

The standard zinc sulphate solution required is best prepared by dissolving about 1.63 g (accurately weighed) of granulated zinc in dilute sulphuric acid, nearly neutralising with sodium hydroxide solution, and then making up to 250 mL in a graduated flask alternatively, the requisite quantity of zinc sulphate may be used. In either case, de-ionised water must be used. 

The amalgamated zinc may be prepared by adding 1500 g. of clean granulated zinc to 600 ml. of 5% mercuric chloride solution. After standing for 2 hours with occasional shaking, the liquid is decanted and the zinc is used immediately. 

Alternatively,21500 g. of granulated zinc is added to a solution of 62.5 g. of mercuric chloride and 62.5 ml. of concentrated hydrochloric acid in 1875 ml. of water. The mixture is shaken for about 5 minutes, the liquid decanted, and the zinc used immediately. 

Experiment.—To a few drops of nitromethane dissolved in a little water some pieces of granulated zinc and then some concentrated hydrochloric acid are added. A vigorous reaction takes... 

Preparation of the Zinc Amalgam. —Granulated zinc in thin pieces or, still better, zinc foil 0-15 to 0-25 mm. thick and cut into small strips, is left for one hour with frequent shaking in contact with an equal weight of 5 per cent aqueous mercuric chloride solution. The solution is then poured off and the metal washed once with fresh water. 

Anhydrous Citric Acid Dissolve 0.8 g in 4 ml DW, add 3 ml HC1 and boil for 1 minute with 1 g granulated zinc. Allow to stand for 2 minutes, decant the liquid into a test-tube containing 0.25 ml phenyl-hydrazine HC1 and heat to boiling. Cool rapdily, transfer to a graduated cylinder, add an equal volume of HC1 and 0.25 ml potassium hexacyanoferrate (III), shake and allow to stand for 30 minutes. Any pink colour produced is not more intense than that produced by treating 4 ml of a 0.01% w/v soln. of oxalic acid at the same time and the same manner (360 ppm, calculated as anhydrous oxalic acid). 

Procedure Weigh accurately about 0.8 g of granulated zinc, dissolve by gentle warming in 12 ml of dilute hydrochloric acid and 5 drops of bromine water. Boil to remove excess bromine, cool and add sufficient DW to produce 200 ml in a volumetric flask. Pipette 20 ml of the resulting solution into a flask and neutralize carefully with 2 N sodium hydroxide. Dilute to about 150 ml with DW, add to it sufficient ammonia buffer (pH 10.0) to dissolve the precipitate and add a further 5 ml quantity in excess. Finally add 50 mg of Mordant Black II mixture and titrate with the disodium edetate solution until the solution turns green. Each 0.003269 g of granulated zinc is equivalent to 1 ml of 0.05 M disodium ethylenediaminetetracetate. 

Diphenylketene has been prepared by action of tripropylamine on diphenylacetyl chloride,2 by treating diphenylchloro-acetyl chloride with granulated zinc,3 and by the action of quinoline on diphenylacetyl chloride.4 It is most conveniently prepared by heating phenylbenzoyldiazomethane—a method first described by Schroeter5 and later used by Staudinger.6... 

Finally, in the recent patent literature, some further processes for the preparation of phosphine were described for example, the treatment of white phosphorus with steam in the presence of phosphoric acid at 275-285 °C. According to a British patent, phosphine is formed when white phosphorus, in aqueous acid, is brought into contact with mercury or zinc amalgam A Japanese patent recommends the treatment of a mixture of white phosphorus and granulated zinc with acids and a small amount of methanol for the preparation of highly pure phosphine. Other patents describe electrolytic processes. Finally, it is mentioned that phosphine is formed by the electrolysis of phosporous and hypophosphorous acid, especially at mercury or lead cathodes. ... 

In the first reports on the use of esters of 4-bromo-2-butenoic acid (191a and b, crotonic acid) and of 4-bromo-3-methyl-2-butenoic acid (191c, senecioic acid), the corresponding Reformatsky reactions with benzaldehyde were performed with the old-fashioned procedure, which required heating the haloester, the aldehyde and granulated zinc in benzene/ether mixtures at reflux temperature. 

Determining the Equivalent of Zinc. (Determine the equivalent of zinc as in the preceding experiment.) Weigh about 1.3 g of granulated zinc on an analytical balance with an accuracy up to 0.01 g. Calculate the amount (by volume) of a 20% sulphuric acid solution that is needed for dissolving the zinc. Measure the calculated amount of acid with a measuring glass and add an excess of 100%. To acce-... 

Action of an Acid on a Metal. Assemble the setup shown in Fig. 42. Put 8-10 pieces of granulated zinc in the test tube, pour in 5 ml of a 20% sulphuric acid solution and close the tube with a stopper provided with a gas-discharge tube with its end drawn out upward. Check the purity of the hydrogen evolving. 

Reduction of a Metal Oxide wear eye protection ). Assemble the apparatus shown in Fig. 44 and check its tightness. Put 40-50 pieces of granulated zinc into a 250-ml flask. Pour anhydrous calcium chloride into U-shaped tube. Put 0.3 g of copper oxide into the wide part of a refractory tube, and a piece of copper gauze or foil (why ) into the gas-discharge tube out of which hydrogen will flow. Pour 100-150 ml of a 20% sulphuric acid solution into the flask. Again check... 

Compounds of Vanadium in Lower Oxidation States. Melt paraffin in a porcelain bowl or test tube. Put seven test tubes with stoppers onto a test tube stand. Pour 10 ml of a sodium vanadate solution into a small 50-ml flask, add 10 ml of a 20% sulphuric acid solution, and put in 8-10 small pieces of granulated zinc. Watch how the solution s colour changes. As a new colour appears, pour off 1-2 ml of the solution into each of three of the tubes. In one of them, pour melted paraffin over each layer of liquid with a new colour. Close the other two tubes with their stoppers and pour the following portion of the solution with a new colour into two empty tubes with stoppers. 

Prepare amalgamated zinc. To do this, place 100 g of granulated zinc into a wide-neck bottle and pour over it a solution of 0.1 M mercury(II) chloride in a 1 A hydrochloric acid solution. Close the bottle with a stopper and shake the mixture for 10-15 minutes, after which wash the amalgamated zinc first with a large amount of distilled water, and then with al jV sulphuric acid solution. Constant-... 

Preparation of Zinc Amalgam. (Perform the experiment on a tray with high sides ) Put two or three small pieces of pure granulated zinc into a 25-ml porcelain bowl and add 3-4 ml of a 2% mercu-ry(II) nitrate solution acidified with 0.3 ml of concentrated nitric acid. Stir the mixture during 10 minutes, then pour o0 the solution and wash the zinc with water by decantation until the liquid becomes absolutely transparent. Store the zinc amalgam in a jar under water. 

Preparation of Zinc Chloride. Assemble an apparatus (see Fig. 61), replacing the funnel with a U-tube containing calcium chloride. Weigh 1-2 g of pure granulated zinc in a porcelain boat and place the latter into a refractory tube. Cover the outlet end of the tube... 

Preparation of Zinc Chloride Crystallohydrate. Put 5 g of granulated zinc into a 50-mI flask, pour in 12 ml of water, and add 13 ml of concentrated hydrochloric acid in small portions. When the reaction slows down, place the flask on a warm water bath and bring the reaction up to its end. Let the flask with its contents stand up to your next lesson. Filter the solution, and test it for the presence of iron(II) ions. If the reaction is positive, saturate the solution with chlorine. For what purpose Tightly close the flask containing the reaction mixture with a stopper and again let it stand up to your next lesson. Heat the flask in a water bath and introduce moist zinc oxide in small portions up to the complete separation of iron hydroxide. How can you determine that the ions of iron have precipitated completely ... 

Into a 500-cc. Erlenmeyer flask put enough granulated zinc to cover the bottom. Pour over this about 150 cc. of absolute alcohol and provide the flask with a two-hole stopper. Through one hole insert a delivery tube dipping under the alcohol and through the other an exit tube... 

Arsenic. —Add 0.1 gm. of potassium chlorate to 200 gm. of hydrochloric acid, and evaporate on the water-bath. A Marsh apparatus is started, using 20 gm. of arsenic-free, granulated zinc and dilute (1 5) sulphuric acid then the... 

Arsenic. -- A Marsh apparatus is sol in opcniliun. using 20 gm. of arsenic-free. granulated zinc,, uiul arsenic free, dilute, sulphuric, acid (I fi). As soon us Ihe air has lieeii expelled from the apparatus, beat Ihe miiit-lion lube l<> redness, and then introduce a cooled mixture of ID cc. of the acid (sp. gr. 1. SI) to be lesled and al) cc. of water. No deposit or arsenic should be visible in the reduction lulte within halt an hour. 

Arsenic. —Introduce 10 gm. of arsenic-free, granulated zinc into the generating flask of a Marsh apparatus, and start the stream of hydrogen by adding dilute (1 5) sulphuric acid. After the apparatus and reagents have been tested in the usual manner, dissolve 2 gm. of calcium biphosphate in 5 cc. of hydrochloric acid and 15 cc. of water. Introduce this solution into the Marsh apparatus, and maintain the flow of gas for about one hour. No deposit of arsenic should be visible in the reduction tube within this time. 

Arsenic. — Pour 100 cc. of hydrochloric, acid over 20 gm. of potassium chlorate in a capacious porcelain dish. As soon as the evolution of chlorine lias slackened) evaporate the solution on the water-bath to dryness. A Marsh apparatus is set in operation, containing 20 gm. of arsenie-free, granulated zinc and dilute (1 5) sulphuric, acid. The residue from the above evaporation, dissolved in 00 cc. of water, is then introdued into the generating flask of Uie apparatus in small portions at a time. No deposit of arsenic, should be visible in the reduction tube within two hours. 

The iodide is now reduced to pentamethylene by mixing it with five times its weight of alcohol and some granulated zinc in a flask fitted with reflux condenser. 

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