Temperature thermometer

It is one of four metals — mercury, cesium, and rubidium — which can be liquid near room temperature and, thus, can be used in high-temperature thermometers. It has one of the longest liquid ranges of any metal and has a low vapor pressure even at high temperatures. 

The technique used here has been described previously by the checkers. Instead, the submitters used a dry 500-mL, three-necked flask equipped with a variable speed mechanical stirrer, a IQQ-mL pressureequalizing dropping funnel topped by a gas inlet and a Claisen head containing a low temperature thermometer (-70 C to +35°C), and a bubbler. A stream of nitrogen followed from the gas inlet. 

A. Ethyl 4-Amino-3-(methylthiomethyl)benzoate [Benzoic acid, 4-amino-3-[(methylthio)methyl]-]. A 1-1., three-necked, round-bottomed flask is fitted with a mechanical stirrer, a condenser topped with a gas-inlet tube, and a two-neckcd adapter holding a low-temperature thermometer and a 100-ml., pressure-equalizing dropping funnel. The flask is charged with 10.50 g. (0.10 mole) of ethyl p-aminobenzoate [Benzocaine Benzoic acid, 4-amino-, ethyl ester] (Note 1), 300 ml. of acetonitrile, and 100 ml. of dichloromethane, is flushed with nitrogen, and is then immersed in a 40% aqueous methanol-dry ice bath maintained between... 

A good low-temperature thermometer should possess several qualities ... 

As we have seen in Section 9.5.3, in the case of resistance thermometry, the signal produced by a low-temperature thermometer is very low (microvolt range). Low-pass filters are not sufficient to narrow the detection bandwidth in order to get a suitable signal to noise ratio (S/N). Bandpass filters are needed. The most commonly used method is the synchronous demodulation, usually simply called lock-in technique, as shown in the block diagram of Fig. 10.7. 

Low-temperature thermometers are obtained by cutting a metallized wafer of NTD Ge into chips of small size (typically few mm3) and bonding the electrical contacts onto the metallized sides of the chip. These chips are seldom used as calibrated thermometers for temperatures below 30 mK, but find precious application as sensors for low-temperature bolometers [42,56], When the chips are used as thermometers, i.e. in quasi-steady applications, their heat capacity does not represent a problem. In dynamic applications and at very low temperatures T < 30 mK, the chip heat capacity, together with the carrier-to-phonon thermal conductance gc d, (Section 15.2.1.3), determines the rise time of the pulses of the bolometer. 

In a cryogenic experiment, one or several detectors are used for a definite goal for which they have been optimized. For example, in CUORE experiment described in Section 16.5, the sensors are the Ge thermistors, i.e. thermometers used in a small temperature range (around 10 mK). One detector is a bolometer made up of an absorber and a Ge sensor. The experiment is the array of 1000 bolometers arranged in anticoincidence circuits for the detection of the neutrinoless double-beta decay. Note that the sensors, if calibrated, could be used, as well, as very low-temperature thermometers. Also the array of bolometers can be considered a single large detector and used for different purposes as the detection of solar axions or dark matter. 

The low-temperature thermometers based on heavily doped compensated germanium (see Section 9.6.2.1) show high stability, good reproducibility, low noise and low specific heat. Ge used for cryogenic sensors is heavily doped (1016 - 1019 atoms/cm3), with T0 of Mott s law ranging between 2 and 70K (see formula 9.6). 

B. Mixed benzoic-carbonic anhydride (Note 7). In a 500-ml. threenecked flask, equipped with a low-temperature thermometer, an efficient sealed stirrer, and an adaptive joint carrying a drying tube and a dropping funnel, is placed a solution of 24.4 g. (0.2 mole) of benzoic acid (Note 8) and 20.2 g. (0.2 mole) of triethylamine (Note 9) in 200 ml. of dry toluene. The solution is cooled below 0° by means of an ice-salt mixture, and 21.7 g. (0.2 mole) of ethyl chlorocarbonate (Note 10) is added at such a rate that the temperature does not rise above 0° (approximate time for addition is 25-30 minutes). Triethylamine hydrochloride precipitates both during the addition and while the mixture is stirred for 15-25 minutes thereafter. 

A 500-ml., four-necked, round-bottomed flask is equipped with an efficient stirrer, a reflux condenser, a 250-ml. dropping funnel, and a low-temperature thermometer (Note 2). In the flask are placed 34.4 g. (21.8 ml., 0.25 mole) of phosphorus trichloride (Note 3) and 150 ml. of anhydrous ether. A solution of 0.50 mole of isopropylmagnesium chloride in about 150 ml. of ether (Notes 4 and 5) is placed in the dropping funnel. 

To a dry 1-1., three-necked flask fitted with an efficient mechanical stirrer, a low temperature thermometer, and a solid addition assembly (Note 11) is added 97 g. (0.30 mole) of dibromoketone and 700 ml. of anhydrous tetrahydrofuran (Note 12). After the reaction vessel has been... 

After ten minutes take the reading by holding the bulb behind the graduated tube with the meniscus in the bulb accurately in the same plane as the meniscus in the tube. Read the scale division which is in the same horizontal plane as the lower edge of the meniscus. Also note the temperature (thermometer in the part of the nitrometer above the stop-cock) and the barometric pressure. 

Electric tube furnaces of appropriate dimensions are available from various manufacturers. A model RO 4/25 by Heraeus GmbH, Hanau, FRG is suitable. However, a very satisfactory furnace can be built by any well equipped laboratory workshop at little cost and effort. The material required consists of thin walled ceramic tubing, 3.5 cm i.d., nichrome resistance wire, heat resistant insulation, and ordinary hardware material. A technical drawing will be provided by the submitters upon request. The temperature of the furnace can be adjusted by an electronic temperature controller using a thermocouple sensor. A 1.5 kW-Variac transformer and any high temperature thermometer would do as well for the budget-minded chemist. 

B. N,N-Diethyl-2-formyl-6-methoxybenzamide (3). An oven-dried, threenecked, 1-L flask equipped with a 100-mL pressure equalizing dropping funnel, nitrogen bubbler, internal low temperature thermometer pocket, and overhead stirrer is flamed under reduced pressure and allowed to cool under a stream of nitrogen. The flask is charged with 500 mL of THF (Note 6) and cooled to an internal temperature of -72°C. N,N,N, N -Tetramethylethylenediamine (TMEDA) (Note 8) (23.5 mL, 0.156 mol) followed by 128.7 mL (0.157 mmol) of 1.22 M sec-butyllithium in cyclohexane (Note 9) are then added. The internal temperature rises a little as the reagents are added. The fluorescent yellow solution is allowed to recool to an Internal temperature of -73°C. 

Uses Solvent recovery and extraction blowing agent for plastic foams low temperature thermometers natural gas processing plants production of olefin, hydrogen, ammonia fuel production pesticide manufacture of artificial ice organic synthesis. 

Because of its high range of temperatures as a liquid (from 29.8°C to 2,403°C), it is used in special types of high-temperature thermometers. It is also alloyed with other metals to make alloys with low temperature melting points. 

Thallium-mercury is an amalgam—not really a compound, but more hke an alloy mixture. It is used in low-temperature thermometers and as a substitute for mercury in low-temperature switches. 

Gallium, like mercury, is liquid at room temperature, but unlike mercury is much less hazardous. Its most interesting use is as a visualization tool of soft tissues and bone lesions in radiography. Industrial applications include use in high temperature thermometers, metal alloys, and as a substitute for mercury in arc lamps. 

A 1-1. three-necked round-bottomed flask equipped with an air stirrer, dropping funnel, and low-temperature thermometer is charged with 38.0 g. (0.2 mole) (Note 1) of 1-phenyloyelopon-... 

A 500-mL, three-necked, round-bottomed flask is equipped with a 25-mL pressure-equalizing dropping funnel, a mechanical stirrer, and a Claisen adapter fitted with a nitrogen inlet adapter and a low temperature thermometer (Note 1). The flask is charged with 11.5 g (0.077 mol) of (R)-(-)-carvone (Note 2), 10.8 g (0.079 mol) of 1-methyl-l-(trimethylsilyl )allene (Note 3), and 180 mL of dry dichloromethane (Note 4), and then cooled below -75°C with a dry ice-acetone bath while a solution of 17.4 g (0.092 mol) of titanium tetrachloride (Note 5) in 10 ml of dichloromethane is added dropwise over 1 hr. After 30 min, the cold bath is removed, and the reaction mixture, which appears as a red suspension, is allowed to warm to 0°C over approximately 30 min. The resulting dark red solution is poured slowly into a 2-L Erlenmeyer flask containing a magnetically-stirred mixture of 400 mL of diethyl ether and 400 mL of water (Note 6). The aqueous phase is separated and extracted with... 

A, Oevanyl ahloTids. To a flame-dried, 100-mL, three-necked, round-bottomed flask equipped with a magnetic stirrer, low temperature thermometer, rubber septum, and nitrogen inlet adapter, is added 1.47 g (11 mmol) of N-chlorosuccinimide (Note 1). The powder is dissolved in 45 mL of dry... 

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