Thermometers, broken

The SPRTs are devices of superb accuracy and resolution, but they are fragile and can easily be broken. They can also be put out of caUbration by strain, iaduced by even slight mechanical shock or vibration. The principal use of SPRTs ia scieace and iadustry is to maintain the cahbrations of working thermometers. 

Fig. 32.9. Thermometer plot representing the scores of the first and second component of a CFA applied to Table 32.10. The solid line denotes the first component which accounts for the women/men contrast in the data. The broken line corresponds with the second component which reveals a contrast between chemistry and other fields.

Mercury drops were often encountered when a thermometer was broken. Mercury is poisonous and banned from households. 

Digital thermometers are safer to use in children than glass thermometers as there is no risk of the glass being broken. Digital thermometers tend to be more expensive. 

Exposure is also affected by absorption. Even though we may come into contact with an agent, if little is taken up into the body (or absorbed), there is little effect. For example, the metallic mercury from a broken thermometer, if swallowed, is very poorly absorbed by the gut and will be excreted in the feces. However, if this same amount of mercury were allowed to evaporate and be inhaled, there would be very serious health consequences. This example shows that metabolism and excretion modify absorption. What is not absorbed (and even some of what is absorbed) may be excreted from the body by various routes, including the urine, feces, and sweat or through exhalation. Excretion reduces the effect because it lowers the amount of toxicant in the body, thus reducing exposure to sensitive organs. 

Mercury thermometers have been used for decades. In some instances their use has been discontinued, such as in infant incubators where it was found that significant mercury vapor concentrations could be achieved if the thermometers were broken in this enclosed environment. Disposal of thermometers and thermostats continues to add significandy to the toxicity of municipal waste. In 1995, discarded thermometers contributed 16.9 tons of mercury to municipal solid waste stream. 

To 1035 g. of syrupy arsenic acid (80-85 Per cent, sp. gr. 2.00/200 Note 1) in a 12-inch evaporating dish, is added 828 g. (800 cc.) of aniline (Note 2) in 100-cc. portions meanwhile, the lumps of aniline arsenate which are formed are broken up by rapid stirring with a porcelain spatula. When all the aniline has been added, the powdered solid is transferred to a 3-I. round-bottom flask equipped with a mechanical stirrer, a thermometer reaching to the lower part of the vessel, and a condenser arranged for downward distillation (Note 3) an additional 800 cc. of aniline is added and the flask slowly heated in an oil bath. The bath may be kept at a temperature not exceeding 170-175° as long as there is any considerable amount of unmelted material in the flask. When the contents of the flask have become liquid the temperature of the bath is dropped and the mixture held at 155-160° (inside temperature), with continual stirring, for at least four and a half hours. The mass will have assumed an intense violet color. 

One would not think that a shiny little sliver of mercury sealed in a thermometer could cause problems, but broken thermometers have resulted in a number of hospitalizations. Children are especially susceptible to the effects of mercury vapor, because of their small size. The symptoms they experience may... 

Typical exposure to mercury in the General Chemistry laboratory occurs during (A) Boyle s Law experiments, (B) thermal decomposition of mercuric oxide, (C) displacement of mercury from its dissolved salts, and (D) cleaning up spills from broken thermometers. 

Occasional accidents involving broken thermometers (D) are almost inevi-... 

Water is distilled from the mixture at atmospheric pressure until the temperature of the solution reaches 115° (Notes 2 and 3) whereupon the liquid is transferred to a 500-ml. round-bottomed flask. This flask is connected to the distillation apparatus used previously except that the thermometer is replaced by a capillary tube. Distillation is then continued under the reduced pressure obtainable from a water aspirator. The bath temperature is raised to 175° over a period of about an hour and is held there until the mixture solidifies (usually 30-60 minutes longer), and for 1 hour thereafter. The flask is cooled and broken to remove the product. 

An alternate technique to rejoin broken liquid columns is to expand the liquid into the contraction or expansion chamber by heat. Be careful to avoid filling the expansion chamber more than two-thirds full, as extra pressure may cause the top of the thermometer to burst. Never use an open flame to intentionally heat any part of a thermometer as the temperature from such a source is too great and generally uncontrollable. 

Bimetallic Thermometers. These use two metals of different coefficients of thermal expansion that are bonded together their heating bends the device, and an electrical contact can then be made or broken. Thermometer coils that expand/contract with temperature and make or break contact with a mercury electrode are used in household thermostats and industrial control apparatus. 

Three hundred and thirty-five grams of the 25% ethanolic solution of benzyltrimethylammonium ethoxide (0.43 mole) is placed under nitrogen in a 3-1. three-necked flask equipped with a gas inlet tube, a gas-tight modified Hershberg stirrer (Note 1), and a gas outlet tube fitted with a thermometer. All stoppers and rubber connections are wired in place with 16-gauge copper wire. There is obtained by evaporation at 40° (Note 9) under reduced pressure (Note 10) 97 g. (0.40 mole) of the ethoxide containing an equivalent of ethanol. The vacuum is broken with dry nitrogen. 

This liquor is then poured in a stainless steel cookie baking tray so that it is 1 / 8 to 3/16 inch deep This tray is then placed in an oven set on the lowest temperature that the oven will operate (160 degrees F, 70 degrees C ideally) This temperature should be checked with a oven thermometer or candy thermometer before the AN liquor is placed in the oven When the proper temperature is achieved, the cookie sheet is placed in the oven with the door slightly ajar to allow the water being driven off to escape This liquor should be allowed to remain in the oven for 18-22 hours The remaining crystals will be very easily broken up and are the ideal crystal structure and size for explosives manufacture... 

In a 500-cc. three-necked, round-bottomed flask fitted with a reflux condenser, mechanical stirrer, and thermometer are placed 48.5 g. (0.22 mole) of the sodium sulfinate and 60 cc. of a mixture of 75 cc. of ethylene glycol and 120 cc. of carbitol or methyl car-bitol. The mixture is stirred and heated in an oil bath until solution is complete, after which 31.5 g. (0.2 mole) of 4-chloronitro-benzene (m.p. 76-78°) is added. The mixture is heated for three and a half hours at 141-143° (thermometer in the mixture), with continued stirring, and then is allowed to cool overnight. After addition of 20 cc. of water, the pasty lumps are broken up, and the solid is filtered with suction and washed with 50-75 cc. of hot water. The solid is then transferred to a 1-1. flask and refluxed with 250 cc. of 95 per cent alcohol for fifteen minutes. After cooling, the -nitro- -acetylaminodiphenylsulfone is filtered with suction and washed on the funnel, first with 25 cc. of alcohol and then with 25 cc. of ether. After drying in the air, the tan-colored solid weighs 32-33 g. (50-52 per cent of the theoretical amount) and melts at 226-228° (Note 2). 

---