Wood s metal

The analysis of low-melting alloys such as Wood s metal is greatly simplified by complexometric titration, and tedious gravimetric separations are avoided. The alloy is treated with concentrated nitric acid, evaporated to a small volume, and after dilution the precipitated tin(IV) oxide is filtered off heavy metals adsorbed by the precipitate are removed by washing with a known volume of standard EDTA solution previously made slightly alkaline with aqueous... 

The first use of lithium alloys as negative electrodes in commercial batteries to operate at ambient temperatures was the employment of Wood s metal alloys in lithium-conducting button-type cells by Matsushita in Japan. Development work on the use of these alloys started in 1983 [10], and they became commercially available somewhat later. 

A. Wood s metal bath or a mixture (m. p. about 150°) of ten parts of potassium nitrate and seven and one-half parts of sodium nitrite may be used. 

Calculate the relative number of atoms of each element contained in each of the following alloys (a) Wood s metal, which is a low-melting-point alloy used to trigger automatic sprinkler systems and is 12.5% tin, 12.5% cadmium, and 24% lead by mass in bismuth (b) a steel that is 1.75% by mass carbon in iron. 

In a 1-1. round-bottomed flask, fitted with a heated reflux condenser maintained at 100-110° (Note 1), are placed 44 g. of stearic acid (Note 2) and 20 g. (0.5 mole) of magnesium oxide (Note 3). The flask is immersed in a Wood s metal bath heated at 335-340° (Note 4). After the reaction has proceeded for 1 hour, 10-g. portions of melted stearic are added down the condenser at 15-minute intervals until an additional 240 g. (284 g., 1 mole total) has been added (Note 5). The heating is continued until the total reaction time is 10 hours. 

C. 3-Methylcoumarone. Dry 3-methylcoumarilic acid (50 g.) is distilled from a 250-ml. Claisen flask fitted with a long air condenser and immersed in a Wood s metal bath heated slowly to 280°. Carbon dioxide is evolved, and a cloudy liquid distils at 190-220°. The crude product is purified by redistillation through a Vigreux column (Note 6). The dear colorless distillate, weighing 31.5-33 g. (84-88%), boils at 195-197°, n 1.5520. 

Hydrogenated cottonseed oil, Coto Flakes, obtainable from the Procter and Gamble Company, Cincinnati, Ohio, is suitable for the bath. A Wood s metal bath may also be used. 

The benzene solution of the diazo compound is poured into a separatory funnel protected with a drying tube and connected to a 125-cc. Claisen distilling flask provided with a condenser set for downward distillation and arranged so that it can be heated in a bath of Wood s metal. The temperature of the metal bath being maintained at 100-110°, the benzene solution is dropped slowly into the hot flask. Under these conditions, the benzene is removed by distillation, and the diazo compound transformed into diphenylketene. The residue is distilled in vacuo in an atmosphere of nitrogen, and the fraction boiling at 115-125° at 3-4 mm. (Note 5) is collected. The yield is 31 g. (64 per cent of the theoretical amount) of a product which, on redistillation, yields 28 g. of diphenylketene boiling at 119-121° at 3.5 mm. (58 per cent of the theoretical amount). 

Wood s metal is another alloy that contains about 12.5% cadmium plus bismuth. It has a very low melting point of about 70°C, which makes it ideal for the fuse in overhead sprinklers in hotels and office buildings. Any fire will melt the trigger-like fuse, opening the valve to jettison water spray over the hot area that melted the Wood s metal alloy. 

TelluranthreneP Finely powdered tellurium (2.3 g, 18 mmol) and 2.5 g (9.0 mmol) of o-phenylenel mercury are intimately mixed by grinding in a mortar, the mixture is placed in the well of a sublimation apparatus, which is then evacuated to <1 torr. The well of the sublimation apparatus is heated at 250°C in a bath of Wood s metal for 10 h, and the cold finger is cooled with dry ice. The sublimed solids are dissolved in chloroform, the solution is decanted through a filter, the solvent is evaporated, and the residue is recrystaUized from carbon tetrachloride or ethanol/benzene. Yield 1.05 g (57%). m.p. 179°C. 

French nobleman Claude Geoffroy, the Younger White, brittle metal often found with copper, tin, and lead its alloy, called Wood s metal, has a low boiling point making it useful in triggering fire alarms. 

In the table which. follows are listed the temps in °C which were detd in the USA by means of apparatus similar to the one described in Ref 28. The values are taken from PATR 1740, Rev (1958) and from the table entitled "Military Explosives compiled at PicArsn. The temps detd in Russia for some expls and reported in Ref 24, p 29 and Ref 25, pp 326-27 are given here for comparison Most of the apparatuses used in foreign countries employ heated baths either filled with Wood s metal or with. some liquid of high bp, such as in apparatus of Kostevitch (Refs 5 24). Exceptions are the apparatus of Lang-hans, briefly described in Ref 4, which employs a metal block and the apparatus of Belgrano (Ref 18) which employs an iron plate and is of very simple construction... 

Explosion Temperature. Accdg to OSRD 1767 it does not explode below 360° when placed on Wood s metal surface, while accdg to OSRD 1986 it explodes at 285°... 

On somewhat smaller runs it may he more convenient to effect heating by the use of a wax or Wood s metal bath or an electric mantle. A hath or mantle temperature of 200° is sufficient for optimum 3neld. The reaction may froth vigorously if heated too rapidly or if the fumaramide is impure. 

Thermal sensitivity Temperature of ignition of FOX-7 is 215 °C as against 220 °C for RDX (Wood s metal bath). Further, excellent thermal stability is indicated by vacuum stability test for both FOX-7 as well as RDX. 

A Wood s metal bath is constructed as follows a solid mild steel block 30 cm long,... 

The test is performed with 20 mg of a sample, ground and dried. When the temperature of the bath is 300 °C, a test tube with the sample is immersed in the Wood s metal bath and a stopwatch is switched on simultaneously. When explosion of the sample occurs, the time is recorded by the stopwatch, that is, the time interval between the moment of insertion and the moment of explosion is noted. This period is the explosion delay (J D) or induction period at that temperature. In order to eliminate accidental variations, the mean of three readings is taken in all cases. The bath temperature may be decided depending upon the value of f D, that is, if value of ED is too high, the bath temperature may be increased whereas if it is too low, bath temperature may be decreased in order to improve the accuracy of the determination. 

A Beckman thermometer is used to read the temperature of the bath. When the temperature of the Wood s metal bath is -300 °C, a test tube with a sample is immersed in it. A stopwatch is used to record the time interval between the moment of immersion of sample in the bath and the moment of its explosion. If the explosion delay (ED) is more than 10/5 seconds, the temperature of the bath is increased by 10 °C and the experiment is repeated with a fresh sample. This exercise is repeated with incremental temperature changes (higher or lower) until an exact ED of 10-/5- seconds is obtained. This method is similar to that described by Weber in the literature [24]. 

Activation Energy It is experimentally seen that the explosion delay (ED) for the build-up of an explosion decreases with an increase in temperature. Therefore, energy of activation (IQ can be calculated on the basis of a relationship between the experimentally obtained ED and the absolute temperature of the Wood s metal bath. This relationship is expressed by an Arrhenius type of equation, that is, (Equation 3.3) ... 

T = absolute temperature of the Wood s metal bath A = frequency factor depending on the explosive. 

Drop Test. See Impact Sensitivity Test Effect of Pressure on Performance in Detonators. See Pressure Effect, etc Explosion(or Ignition) Temperature. When O.02g charges of pentryi were dropped on molten Wood s metal preheated to various temps, no expin or ignition took place at 233°(5 trials), but at 235° the sample ignited in 3 secs after it touched the hot surface. The same time interval was observed at 240°, while at 250° it was 2 secs, at 260° 1.5 to 2 secs and at 270—280° 1.5 secs (Ref 4,p 1389)... 

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