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Laboratory preparation of metal

Preparation of manganese Aluminothermic

The basic ingredient for the preparation of manganese oxide Manganomanganic which we obtain by heating manganese dioxide in a porcelain crucible n 1000-1100 ° C. To avoid the loss of manganese in the slag, which is present as divalent manganese aluminate will prevent the addition of calcium oxide. A mixture of 20.7 g prepare manganomanganic oxide, 5.5 g of aluminum and 3.6 g of freshly annealed calcium oxide. After mixing the mixture is placed in fireclay crucible and ignite. The slag remains 20% manganese in the form of aluminate.

Preparation of chromium Aluminothermic

A mixture consisting of 60 g chromium oxide, 12 g of melted anhydrous chromium trioxide and 27 g of aluminum powder. The carbon chromitému adding chromium trioxide and spread well. To this mixture add the aluminum powder and stir. Finally, place the mixture in a fireclay crucible ignite.

The thus obtained chromium contains 0.2 to 0.3% aluminum. Instead of chromium oxide can be used potassium dichromate: 25 g of potassium dichromate, 35 g chromium oxide and 17 g of aluminum

Preparation of vanadium Aluminothermic

A mixture consisting of 100 g of melted and minced vanadium oxide powder, 49.5 g of aluminum powder and 10 to 15% calcium fluoride (percentages are relative to the weight of the base mix - fluoride acts as a flux). Obtained after separation of vanadium from slag briefly dip the end. hydrochloric acid to be purified, then rinsed with water and dry. The alloy contains 95-96% vanadium.

Preparation bismuth reduction with hydrogen

Bismuth oxide is placed on a boat in a glass tube, the apparatus vytěsníme air stream of hydrogen. After neagativní test for Explosive Gas begin tube heat pumps in place at 380-400 ° C while the apparatus introducing hydrogen stream. Metal is obtained in the form of a melt with a pink tinge.

Bi 2 O 3 + 3H 2 -> 3BI + 3H 2 O

Preparation of bismuth reduction of fructose

Bismuth can be prepared by reducing agents Nylanderova glucose (fructose). 1 liter Nylanderova agent boil about 30 minutes with a solution of glucose xg vx ml water. Excluded red-brown precipitate of bismuth decanted about 2 liters of water, apply suction and dry.

Preparation Nylanderova agents: K 15.4 g 4BiNO 3 · Bi (OH) 2 (used as a normal bismuth nitrate, only need to recalculate the amount and the amount of hydroxide), add 40 g of sodium potassium tartrate in 400 ml of water and 100 g sodium hydroxide in 300 ml water, dissolve and add to 1 liter with water. Yield: about 6 g (50%).

Preparation of cadmium electrolytically

Powder cadmium prepare electrolysis solution CDCl 2 .5/2H 2 and 300 g of NaCl per liter of water added. Electrolysis at 20 ° C, pH = 6 and the cathode current density of 0.5 A / dm 2 using platinum electrodes.

Preparation of copper cementation

Powder copper prepare reacting an aqueous solution of copper sulfate and zinc powder. To 20 g of copper sulphate pentahydrate in 500 ml beaker xg adding zinc powder and for about 2 hours mix. Originally blue solution was decolorized (solution containing zinc sulphate). Pour off solution Decant water and add about 100 ml of hydrochloric acid (1:1), thereby getting rid of the unreacted zinc, which are added in excess. After 30 minutes pour solution, copper decanted several times with water, sucked off and dried in a desiccator the absence of air (the copper oxidizes in air).

CuSO 4 + Zn -> ZnSO4 + Cu
Zn + 2HCl -> ZnCl 2 + H 2

Preparation of thermal decomposition of mercury oxide

In a test tube fitted with a stopper pierced with a long tube about 30 cm (functions as air coolers) placed 10 g oxide and tube heat the gas burner. Carbon covers and the resulting mercury collects in the bottom of the tube. Mercury vapor is toxic!

2HgO -> 2HG + O 2

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