Ovens electric

Anhydrous oxalic acid may be prepared by heating the finely-powdered A.R. crystallised acid, spread upon large clock glasses, in an electric oven at 105° for 6 hours, allowing to cool in a desiccator and storing in a tightly stoppered bottle. 

Preparation of silver maleate. Dissolve 65 g. of pure maleic acid (Section 111,143) in the calculated quantity of carefully standardised 3-5N aqueous ammonia solution in a 1-htre beaker and add, whilst stirring mechanically, a solution of 204 g. of silver nitrate in 200 ml. of water. Filter oflf the precipitated silver maleate at the pump, wash it with distilled water, and press well with the back of a large flat glass stopper. Dry in an electric oven at 50-60° to constant weight. The yield of the dry silver salt is 150 g. Store in a vacuum desiccator in the dark. 

Lead nitrate [10099-74-8] M 331.2, m 470°. Ppted twice from hot (60°) cone aqueous soln by adding HNO3. The ppte was sucked dry in a sintered-glass funnel, then transferred to a crystallising dish which was covered by a clock glass and left in an electric oven at 110° for several hours [Beck, Singh and Wynne-Jones Trans Faraday Soc 55 331 1959], After 2 recrystns of ACS grade no metals above 0.001 ppm were detected. 

Electric ovens. The most convenient type is an electrically heated, thermostatically controlled drying oven having a temperature range from room temperature to about 250-300 °C the temperature can be controlled to within 1 -2 °C. They are used principally for drying precipitates or solids at comparatively low controlled temperatures, and have virtually superseded the steam oven. 

Air baths. For drying solids and precipitates at temperatures up to 250 °C in which acid or other corrosive vapours are evolved, an electric oven should not be used. An air bath may be constructed from a cylindrical metal (copper, iron,... 

After thorough rinsing with distilled water, the electrode is rinsed with 15-20 mL of pure acetone delivered from a small all-glass wash bottle, and is then placed on a clock glass and dried for 3-4 minutes in an electric oven at 110 °C. After cooling for about 5 minutes at the laboratory temperature, it is weighed and is then ready for the determination. 

The reactor consists of a small cylindrical metal tube (length 100 mm, internal diameter 7 mm) heated by an electric oven and mounted within an assembly which accommodates supply lines, gas/liquid separator, pump and... 

Weigh 50 g of sample into the headspace flask with a magnetic stirrer bar. Add immediately 50 mL of 1.5% stannous chloride solution in hydrochloric acid, and close the vessel with the silicone-rubber septum and the screw-cap. Transfer the head-space flasks into the electric oven (or water-bath) heated at 80 °C for 1 h. After 15 min, take the flasks out of the oven and mix the contents with the magnetic stirrer, heated at 50 °C, for 1 min. Return the flasks to the electric oven and repeat the mixing of the samples every 15 min. After 1 h, take the flasks out of the oven, mix the contents of each flask for 1 min, and inject an aliquot of headspace (100-1000 xL) on to the GC column with a gas-tight syringe. 

The salt exploded during drying at 60-100°C in an electric oven, presumably because of overheating which caused pyrolysis to 3-pentanone and ignition of its vapour. 

Figure 4 Schematic of an oxygen uptake device. 1, sample 2, electrical oven 3, Hg manometer 4, intermediate vessel for pressure adjustment 5, drying vessel 6, control thermometer 7, outlet to vacuum pump and 8, inlet for gas feeding. Reproduced with permission from Zaharescu [10]. Springer 2001.

Catalytic activity was determined with a fixed bed microreactor which consisted of two coassial quartz tubes (i.d. 35 and 16 mm) to allow feed gas preheating and heated in an electrical oven (Watlow) with a temperature controller. The bed temperature was monitored by A K-type thermocoupling. On-line analysers (ABB) for CO, C02, CH4, ... 

Drying, usually by physical methods, is one of the most common unit operations in both laboratory or industrial scale process chemistry, and since heating is usually employed to remove volatiles, thermally unstable materials may decompose if overheated. As a light-hearted example, when a faulty oven thermostat led to overheating of mercuric thiocyanate, a monstrous Pharaoh s serpent resulted. Drying moist cadmium propionate in an electric oven led to explosive ignition of the diethyl ketone vapour produced as an unforeseen by-product. Drying 3,5-dinitro-2-toluamide had more serious consequences. 

Drive wheels for microwave ovens, handles for electric ovens and other household appliances, parts for spit-roasters, air vents for slide projectors. 

A small sample of expl was placed betw an anvil and plunger of a small hydraulic press where it was compressed in the form of a tablet to ca 2500kg/cm. Then the press with the tablet was placed in an electric oven where it was heated for exactly 3 minutes at the temp close, but below, temp of decomposition reported in the literature. Then the sample was cooled to RT and dropped on the bottom of a metallic dish preheated to the temp slightly above the one used in the test. Parallel with this test, a 2nd sample of the same expl was compressed in cold to ca 25000 kg/cm, removed from the press and heated for 3 mins at atm pressure and at the... 

Preparation of dry sample. Transfer two 35g portions of the sample to two 2j4 inch glass funnels, each funnel having a filter paper folded and inserted in it. With the aid of suction, wash the Hg fulminate with enough 95% ethyl alcohol to remove most of the water. Place the filter paper holding the Hg fulminate in a small evaporating dish and dry in a sealed unit electric oven or a steam oven at 40°C—50°C to constant weight... 

Note All glassware used in the above procedure was washed sequentially in soap solution, water, and acetone. The glassware was dried in an electric oven (at 120 °C) for at least 3 h. 

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