Heating devices steam bath

A steam bath looks like the single hole water bath except that there is no heating element and no constant level device. Steam baths require piped steam as their source of heat usually provided by a steam line, which is a permanent supply in the laboratory. 

For temperatures up to 100°, a water bath or steam bath is generally employed. The simplest form is a beaker or an enamelled iron vessel mounted on a suitable stand water is placed in the vessel, which is heated by means of a flame. This arrangement may be used for non-inflammable liquids or for refluxing liquids of low boiling point. Since numerous liquids of low boiling point are highly inflammable, the presence of a naked flame will introduce considerable risk of fire. For such liquids a steam bath or an electrically-heated water bath, provided with a constant-level device, must be used. If the laboratory is equipped with a... 

In a 1 litre round-bottomed flask provided with an efficient double surface condenser, place 40 g. (39 ml.) of aniline, 50 g. (40 ml.) of carbon sulphide CAUTION inflammable) (1), and 50 g. (63-5 ml.) of absolute ethyl alcohol (2). Set up the apparatus in the fume cupboard or attach an absorption device to the top of the condenser (see Fig. 11, 8, 1) to absorb the hydrogen sulphide which is evolved. Heat upon an electrically-heated water bath or upon a steam bath for 8 hours or until the contents of the flask sohdify. When the reaction is complete, arrange the condenser for downward distillation (Fig. 11, 13, 3), and remove the excess of carbon disulphide and alcohol (CA UTION inflammable there must be no flame near the receiver). Shake the residue in the flask with excess of dilute hydrochloric acid (1 10) to remove any aniline present, filter at the pump, wash with water, and drain well. Dry in the steam oven. The yield of crude product, which is quite satisfactory for the preparation of phenyl iao-thiocyanute (Section IV.95), is 40-45 g. Recrystalhse the crude thiocarbanihde by dissolving it, under reflux, in boiling rectified spirit (filter through a hot water funnel if the solution is not clear), and add hot water until the solution just becomes cloudy and allow to cool. Pure sj/m.-diphenylthiourea separates in colourless needles, m.p, 154°,... 

In the case of solutions of flammable liquids having a boiling point below 100 °C, the stainless steel electrically-heated water bath or steam bath provided with a constant-level device must be used. The individual circular type is provided with a series of concentric rings in order to accommodate flasks and beakers of various sizes. A rectangular type, suitable for use in student classes, has several holes each fitted with a series of concentric rings. In both cases the water bath is fitted with an immersion heating element controlled by a suitable regulator. 

If you are fortunate enough to work in a facility that has self-generated steam, you can easily attach one end of a hose to the outlet and the other end to the steam bath or other steam delivery device. Be sure to use heavy-duty flexible tubing to withstand the high heat of the steam, and use as short a piece of tubing as possible so the steam will not condense before it gets to the steam pot. 

A solution of sodium methoxide is prepared from 50 g. (2.17 g. atoms) of freshly cut sodium and 600 ml. of absolute methanol (Note 1) in a 3-1. three-necked flask placed on a steam bath and equipped with a sealed stirrer (Note 2), dropping funnel, and a condenser set downward for distillation (Note 3). To the stirred solution is added in one portion 344 g. (4.0 moles) of 7-butyro-lactone (Note 4), and the flask is heated until methanol distils at a rapid rate. After 475 ml. of methanol is collected, a filter flask or other suitable device equipped with a side arm is connected to the condenser. This receiver is surrounded by an ice bath, and reduced pressure from an aspirator is applied cautiously (frothing) with continuous stirring. An additional 50-70 ml. of methanol is collected in this way. The residue presumably is dibutyrolactone (Note 5). 

In experiments where a precipitate has been formed, collected on a filter paper, and washed free of solution, the sample must be dried before it is weighed for the purpose of determining a yield or performing any kind of analysis. Three common devices for drying solids in general chemistry are an oven, a steam bath, and a heat lamp. 

The most common heating devices are heating tapes and mantles and sand, water, steam, wax, silicone oil, and air (or nitrogen) baths. These should be used in such a way that if an explosion were to occur the heating medium would be contained. Heating baths should consist of nonflammable materials. All controls for heating and stirring equipment should be operable from outside the shielded area. (See Chapter 6, section 6.C.5, for further information.)... 

Perhaps the most common types of electrical equipment found in a laboratory are the devices used to supply the heat needed to effect a reaction or a separation. These include ovens, hot plates, heating mantles and tapes, oil baths, salt baths, sand baths, air baths, hot-tube furnaces, hot-air guns, and microwave ovens. The use of steam-heated devices rather than electrically heated devices is generally preferred whenever temperatures of 100 °C or less are required. Because they do not present shock or spark risks, they can be left unattended with assurance that their temperature will never exceed 100 °C. 

A double boiler is used when a careful control of temperature is required in cooking. Water is boiled in an outside container to produce steam, and the steam condenses on the outside walls of an inner container in which cooking occurs. (A related laboratory device is called a steam bath.) (a) How is heat energy conveyed to the food to be cooked in a double boiler (b) What is the maximum temperature that can be reached in the inside container ... 

Water baths are the more common of the two, and the steam is generated by heating water with an electric element - just like a kettle. The element may have a thermostatic control, which can control the temperature of the water to some extent. Most water baths have a constant level device on the side of the bath, which supplies water to the bath to a fixed level above the heating element and prevents the water bath from boiling dry. Water baths are single hole or multiple hole types, and the holes are covered by concentric metal or plastic rings, which allows you to vary the size of the hole. 

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