Electric flask heater

Remove the stopper from receiver 2 and introduce copper shavings. Close the flask with a stopper provided with a dephlegmator and thermometer (see Fig. 20). Wrap the flask in asbestos and put it into an electrical flask heater. What is the boiling point of vanadium oxychloride Transfer the collected liquid into a weighed drawn out test tube. (Wear eye protection, seal the substance in the presence of your instructor ) Weigh the ampoule with the remaining part of the tube. Calculate the yield in per cent. 

Preparation of Hydroxylamine Chloride. Dissolve 7 g of sodium hydroxide in 30 ml of water and saturate the solution with sulphur dioxide to an acid reaction, after which pass the stream of gas through the solution for another five minutes (in a fume cupboard ). Add the solution dropwise with continuous stirring to a solution containing 5.5 g of sodium nitrite in 9 ml of water cooled by a mixture of ice and salt. See that the temperature does not rise above 0 °C. Pour the solution into a round-bottomed flask, dilute it to a volume of 150 ml, and heat it to boiling on an electrical flask heater. Perform complete precipitation of the sulphate ions with a solution of barium chloride prepared by dissolving 37 g of barium chloride dihydrate in 45 ml of water. 

I) polyethylene wash bottle (m) single-pan electronic balance with automatic zeroing and digital readout, 100 g 0.001 g capacity (n) electric flask heater (o) solid-state control for electric flask heater (p) stainless steel spatula (q) Keck clamp. 

FIG. 1 Reflux apparatus. A steam bath or electric flask heater Is preferred to a burner. 

When the reaction is complete add 75 mL of water to the hot mixture, heat over a hot electric flask heater and steam distill until the tetrachloroethylene is eliminated and the product separates as an oil or semisolid. Cool the flask to room temperature, decant the supernatant liquid into a separatory funnel, and extract with dichloromethane. Run the extract into the reaction flask and use enough more dichloromethane to dissolve the product use a Pasteur pipette to rinse down material adhering to the adapter. Run the dichloromethane solution of the product into an Erlen-meyer flask through a cone of anhydrous sodium sulfate in a funnel and evaporate the solvent (bp 41°C). The residue is a tan or brown solid (8 g). Cover it with methanol, break up the cake with a flattened stirring rod, and crush the lumps. Cool in ice, collect, and wash the product with methanol. The yield of colorless, or nearly colorless, 5,5,10,10-tetrachloro-tricyclo[7.1.0.0 ]-decane is 3.3 g. This material, mp 174-175°C, consists almost entirely of the cis isomer. Dissolve it in ethyl acetate (15-20 mL) and let the solution stand undisturbed for crystallization at room temperature. The pure cis isomer separates in large, prismatic needles, mp 175-176°C. 

The method of supplying the electric flask heater with a constant current can be unreliable since it involves frequent checking of the load, especially if there are large differences in the heats of evaporation of the components being distdled. As the pressure drop in a column depends on the vapour velocity (section 4.11), it provides a convenient means for controlling the heater. The method also has the advantage of not being seriously affected by mains fluctuations or by variations in the gas pressure [13]. 

Figure 7-3 Kjeldahl distillation unit employs electric immersion heater in flask at left to carry out distillation in 5 min. Beaker at right collects liberated NH3 in standard HCI.

Hot Plates. These devices have a metal (cast aluminum, stainless steel, or some alloy), ceramic, or pyroceramic top. Underneath the top is an electric resistance heater. Hot plates are used for heating flat-bottom containers such as beakers and Erlenmeyer flasks. Because hot plate tops are non-porous, there are fewer concerns for spills affecting the heating elements as there are with heating mantles. Magnetic stirring devices are commonly included with hot plates. 

Fig. 316 shows suspended vessels which are available in sizes of 16 to 1501 [1,5]. Adapters for connecting the necks to ball and conical ground joints can be purchased for both types. Flasks of this size are best heated by steam, by some kind of bath, or by electric immersion heaters or mantles. 

Figure 10 9 Kjeldahl distillation unit employs electric immersion heater in flask at left to carry out distillation in 5 min. Beaker at right collects liberated NH, in standard HCl. Round bulb at the top center is a baffle to prevent liquid from bumping over into the receiver. [Rsher Scientific, Pittsburgh, PA.)...

Electric heating Bmi ray electric bunsens suitable (minimum loading 375 watts) or Kjeldahl digestion flask heaters with flask supports (100 ml flask size). 

Distillation apparatus (Fig. Gl.5.4) 500 ml round-bottom flask with 24/40 neck attached to an adapter with a 28/15 ball connected to a 250-ml flask Glass beads Electric heater 25-ml buret... 

Experimental method. In the flask P (see Fig. 1) a mixture was made up at an initial pressure of 200 mm and a temperature of 20° C. Then an electric heater was fitted on to the flask which was heated together with the explosive mixture in it. We estimated the temperature of the mixture by the change in pressure. After a steady temperature was reached (varying in different experiments between 200-300° C) the mixture was exploded. The heater was then removed and the nitric oxides determined as in 3. It was shown by special experiments that even after the flask had been in the heater for fifteen minutes there was no loss of nitric oxide after the explosion. In some experiments the mixture was cooled before the explosion, the flask P being wrapped in a cloth and abundantly wetted with liquid nitrogen. 

The distillation apparatus is shown in Fig. 1. The upper part of the flask and the short column are wrapped in electrical heater tape, which is operated during distillation of the product. 

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