Cleaning forming section

The silver-silver chloride electrode (Ag AgCl) is easily and cheaply made. Two silver electrodes are cleaned (see Section 9.1.1 above) and immersed in aqueous KCl solution (a concentration of 0.1 mol dm is convenient). Next, a potential of about 2 V is applied across them for c. 10 min, causing a thin outer film of silver chloride to develop on the positive electrode. Solid AgCl is formed by a two-step reaction, involving first the electro-formation of silver ion ... 

Cr(VI) is probably the most widely used and versatile laboratory oxidizing agent and is used in a number of different forms to carry out selective oxidations in this text. But from an environmental standpoint, it is far from ideal. Inhalation of the dust from insoluble Cr(VI) compounds can lead to cancer of the respiratory system. The product of the reaction (Cr(III)) should not be flushed down the drain because it is toxic to aquatic life at extremely low concentrations, so, as stated in the Cleaning Up section of the dichromate oxidation experiment, the Cr(III) must be precipitated as insoluble Cr(OH)j, and this material dealt with as a hazardous waste. 

Use the apparatus detailed in Section 111,20. Dissolve 100 g. (123 ml.) of methyl n-butyl ketone (2-hexanone) (Section 111,152) in 750 ml. of ether and add 150 ml. of water. Introduce 69 g. of clean sodium in the form of wire (or small pieces) as rapidly as possible the reaction must be kept under control and, if necessary, the flask must be cooled in ice or in running water. When all the sodium has reacted, separate the ethereal layer, wash it with 25 ml. of dilute hydrochloric acid (1 1), then with water, dry with anhydrous potassium carbonate or with anhydrous calcium sulphate, and distil through a fractionating column. Collect the fraction of b.p. 136-138°. The yield of methyl n-butyl carbinol (2-hexanol) is 97 g. 

Place 50 g. of o-chloronitrobenzene and 75 g. of clean dry sand in a 250 ml. flask equipped with a mechanical stirrer. Heat the mixture in an oil or fusible metal bath to 215-225° and add, during 40 minutes, 50 g. of copper bronze or, better, of activated copper bronze (Section 11,50, 4) (1), Maintain the temperature at 215-225° for a further 90 minutes and stir continuously. Pour the hot mixture into a Pyrex beaker containing 125 g. of sand and stir until small lumps are formed if the reaction mixture is allowed to cool in the flask, it will set to a hard mass, which can only be removed by breaking the flask. Break up the small lumps by powdering in a mortar, and boil them for 10 minutes with two 400 ml. 

For small-scale laboratory work, the exhaust surface is often made as a separate section added to the side of a table or put into a large hole in a table. These tables usually have a sheet metal surface that is resistant to the chemicals used and is easily cleaned. Many circular holes are cut into the metal surface to allow for airflow. This perforation makes the pressure difference over the table quite high and at the same time gives an even distribution of the airflow over the entire surface. These types of exhaust surfaces could be formed to suit different working conditions, e.g., the surface could be made to fit into a sink or to be placed below and around a balance. Using side walls that are not too high, on three or four sides, transforms the table to a partial enclosure, which increases... 

Low-alloy steels can be obtained as structural sections or in sheet form, and must be blast-cleaned to remove the millscale before exposure. Such material has been widely used in North America for highway bridges and for architectural purposes, and also to some extent in the UK and Europe. 

Electrolytic Tinplate. Much of the tin mill product is made into electrolytic tinplate (ETP). A schematic of an ETP cross section is given in Figure 1. The steel strip is cleaned electrolytically in an alkaline bath to remove rolling lubricants and dirt, pickled in dilute mineral acid, usually with electric current applied to remove oxides, and plated with tin. It is then passed through a melting tower to melt and reflow the tin coating to form the shiny tin surface and the tin-iron alloy layer, chemically treated to stabilize the surface to prevent growth of tin oxide, and lubricated with a thin layer of synthetic oil. 

Whole-body dosimeters are processed post-exposure as follows. The whole-body dosimeter is laid on a table covered with fresh aluminum foil and is sectioned into various pieces using a solvent-cleaned pair of scissors. The whole-body dosimeter is usually cut just at the knees to provide two lower leg sections, at the waist to provide an upper leg section, at the elbow to provide two lower arm sections, at the edge of each shoulder to provide two upper arm sections, and across the shoulders and down each side of the chest area to provide a front torso and back torso sample. The two-dosimeter sections from symmetrical parts of the body are combined to form one sample and wrapped in aluminum foil prior to storage. The upper leg, front torso, and back torso pieces are kept separate, and each is wrapped in aluminum foil prior to storage. 

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