Preparation of bromobenzene Bromobenzene: To the round bottom flask fitted with stirrer, reflux condenser and dropping funnel 50 g of dry benzene and 0.5 g of pyridine (to act as a halogen carrier) are placed. From the dropping funnel 120 g (40 ml) of bromine are slowly added. A vigorous reaction begins at 25-30° C with evolution of hydrogen bromide. When the reaction has moderated, the temperature is slowly raised to 65-70° C and maintained at this point until the evolution of hydrogen bromide has almost ceased. After cooling, the contents of the flask are well washed with dilute solution…
Author: Ethan Frank
Preparation of Lead(II) nitrate Lead(II) nitrate: Lead nitrate is one of the most readily prepared salts of lead. Lead oxide (litharge), lead carbonate or metallic lead is treated with an excess amount of concentrated nitric acid. When the reaction mixture cools the crystals of lead(II) nitrate crystallizes. Lead(II) nitrate is separated by filtration and purified by recrystallization. If an insufficient amount of nitric acid is used, the basic salt of lead nitrate (Pb(OH)NO3) forms, which separates as a fine granular or flaky precipitate when the solution cooled. Synthetic inorganic chemistry, by A. A. Blanchard, 277-278, 1936 Into an apparatus as illustrated…
Preparation of p-benzoquinone benzoquinone – quinone Quinone usually is prepared by the oxidation of aniline in acid solution with sodium dichromate. On a laboratory scale the yield is only about 35% and the process is somewhat lengthy. A rapid method of preparing pure Qunione consists in oxidizing hydroquinone with manganese dioxide in an acid medium and removing the product from the reaction mixture by steam distillation. Oxidation of hydroquinone is a more satisfactory regarding starting material than aniline for the laboratory production of Q. Furthermore, the yield is much better. The reaction is carried out in a 2-liter flask having a…
Preparation of Cyclohexanol Cyclohexanol: For the preparation of nickel catalyst, small pieces of pumice stone of a convenient size are soaked in a concentrated solution of nickel nitrate in distilled water, and heated in a basin over a free flame until the nitrate has been converted into the nickel oxide. Cyclohexanol: Alternatively, the pumice is impregnated with a paste of its own weight of nickel oxide and distilled water, and dried on a water bath. The nickel oxide is reduced by heating in a current of pure, thoroughly dried hydrogen in a combustion tube. A combustion tube 1 metre long is…
Preparation of Aluminum Sulfide Aluminum sulfide can be prepared directly from aluminum and sulfur, but when the finely divided substances are mixed and the mixture is heated, either the sulfur entirely distils off without any reaction taking place, or if a reaction starts it is too violent to control. Lead sulfide could be as a source of the sulfide ion because this substance is not volatile and cannot escape before it reacts, furthermore, the reaction is not too violent. 359 g of powdered lead sulfide and 27 g of granulated aluminum are mixed together. The mixture is transferred in the clay…
Synthesis of Potassium Sulfide Preparation of potassium sulfide By treating potassium hydroxide with an excess of hydrogen sulfide potassium hydrosulfide (KHS) forms, which with further treatment with the same quantity of potassium hydroxide yields potassium sulfide: Hydrogen sulfide is passed through 3 parts of concentrated potassium hydroxide solution until no further absorption takes place. Then 2 parts of concentrated potassium hydroxide solution is added in order to neutralize potassium hydrosulfide. The rule, however, is to add only two-thirds of the quantity of solution of potassium hydroxide, as it is better the preparation should contain a little potassium hydrosulfide than that free…
Synthesis of Sulfur Trioxide Preparation of Sulfur Trioxide Sulfur trioxide is formed by reacting sulfur dioxide with oxygen in the present of platinum catalyst. 40 cm long, hard melted glass tube is connected to the ice-cooled receiver. In the tube 10 cm platinized asbestos is placed. Platinized asbestos could be prepared by treating asbestos with the 5 ml of 10% chloroplatinic acid solution and then drying and applying red heat. Heated chloroplatinic acid decomposes and the fibers of asbestos is covered by platinum (catalyst). Platinized asbestos after each use should be well washed with water and heated in the red…
Synthesis of Hydroiodic Acid Preparation of Hydroiodic Acid Hydroiodic Acid: Rubber stoppers, as well as direct light, should be avoided in all operations with iodine, hydrogen iodide and hydroiodic acid. Platinized asbestos is prepared by soaking 3 g of asbestos in 7 ml of 10 % hexachloroplatinic (IV) acid, evaporating the mixture to dryness, and igniting the residue at red heat. A 250-ml distilling flask with a short side-arm at least 10mm wide. The flask is fitted with a gas inlet tube reaching just above the surface of 100g of pure iodine contained in the vessel. The flask is connected…
Synthesis of Hydrobromic Acid Preparation of Hydrobromic Acid Hydrobromic Acid: Of the six methods given here, the first three may be used for the production of gaseous hydrogen bromide as well as for aqueous solutions of the gas; rest of them could be employed only for making the constant-boiling hydrobromic acid acid. The apparatus for hydrobromic acid is made of a gas-washing bottle filled with water, connected to a distilling flask filled with 50 ml of bromine cooled in ice with the inlet tube leading almost to the bottom of the flask. The inlet tube is connected to a Pyrex…
There are more than five billion iPhone users worldwide, which represents 66% of the population. Technology advances are making it easier for people to communicate with each other. While iPhones are great and help make life more convenient, they don’t come without problems. There are a number of common iPhone problems that people experience. Some issues have easy fixes and others require more work. This guide is going to tell you about three common issues and how to fix them. Keep reading so you’re prepared if your iPhone starts acting abnormally. 1. Frozen Screen One of the most frustrating issues…