Calculation of cryoscopic data

Saylor, Charles Proffer

doi:10.1016/s0003-2670(00)86997-4

Cited by 16 publications

(9 citation statements)

References 0 publications

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“…Under the ass nmptions made in section 2, the time-temperaturc m el ting curve is hyperbolic, wh ere 'II r epresents the in tersection of th c hyperbola with the liquid-wfLl'Iliin g cun'e and Tin repr ese nts the temp eratu re co rrespondin g to the horizontal asymptote of li te hyperbola. One of th.e better ways of antti.vzillg' t lt c experilll euttLI data lies in the direct comparison of Lhe cxpcl'illl ental curve with that of a m athematically eXfLct hyperbola [4] . In this optical proj ection m ethod, the mathenutti cally exact hy perbola is projected, by m eans of a photogra phic enlarger, upon the experimental curve.…”

Section: Methodsmentioning

confidence: 99%

“…From tbi s eHeat, at later times in the run, the recorded temperatures will tend to be high. (4) In unsLin-ed svstems the distribution of th e solid throughout tile cell may markedly change the thermal conduction pattern throughout the freezing. Further, in stirred systems, an increasing proportion of solid in the solid-liquid mixture increases the resistance to stirring, causing the stirring energy to increase and the obsenT ed temperatures to be high.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Principles of cryometric impurity determination as applied to samples of small sizes

Saylor¹,

Ross²

1964

J. RES. NATL. BUR. STAN. SECT. C. ENG. INSTR.

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A co nsideration of the faclo rs that tend to prevent attainmen t of t hermal a nd t hermod.vna mic1equ ilibrium d ur ing t hermometri c m etl;ods of purity an alysis s uggests t lmt t he p r o~1 ems. la rgely o n glll ate from sp onta neously. llltr oclucecl inequali ties i n com p os it ion . D un ng eit her a fr eeZin g or m el tlllg cycle, t he soh d phase settl es in t he liqu id. T his r eslil ls i n a greater a \'er age puri ty i n the boLlo m t han in t he upper part of t he \" esse!. TIle effecls would be par ticul a rly s trong duri ng a melling sequence \\ 'here the liquid released by melting of t he solid " -ould prov ide t he co mpositio n al en vironm ent for t he establis hment of fin a l temperature. This hyp ot hesis has been tested by t he des ign of a new cell f or s mall samples. The dcsig n inco rp orates use of s mall go ld p a ns to hold solid and liqui d in close contact. T he resul ts are co mpar able i n precision Lo t hose from conventional t i me-temperature curves witll muc h la rger samples, a co nd iLion not ordinarily p os ible wit h small samples.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Principles of cryometric impurity determination as applied to samples of small sizes

Saylor¹,

Ross²

1964

J. RES. NATL. BUR. STAN. SECT. C. ENG. INSTR.

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“…The purities of the first two compounds were determined by the fr eezing point m ethod [5,6,7] before and after purification. The analyses indicated that before purification the toluene was 99.4 mole percent and the ethylbenz ene 99.1 mole percent pure.…”

Section: Methodsmentioning

confidence: 99%

Purification by automatic gas chromatography

Tenenbaum¹,

Howard²

1962

J. RES. NATL. BUR. STAN. SECT. A.

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A completely a utomatic apparatus h as been develop ed for t he prepa rative-scale p urification of compo unds by gas-liquid chromatograph y. A clock timer periodically activates a pump t hat injects a sample into the column . The recording potentiometer o n which t he chromatogra m is t raced has a swit ch m oun ted at t he upper margin. Collection of t he p urified main component occurs when t he recorder p en goes to t he end of the scale and t rips t he swi tch . The sensitivity of the detector bridge circuit is adj usted so that only t he t race caused by t he major component will activate the collection process.T oluene, ethylbenzene, and mesitylene were purified wit h the apparatus. Best results were obtained with tolucne. In one pass t hrough t he apparatus, 92 percen t of the impurities were removed fro m the toluene and t he p urified product was collected at a rate of 25 ml of liquid per day.

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“…Many authors [42,45] have suggested that it may be necessary for the temperature at the solidliquid interface to be significantly below the equilibrium temperature if freezing is to take place rapidly; i.e., the net rate of freezing is zero at the equilibrium temperature and increases only with decreasing solid-liquid interface temperatures. The metal in the two phases at the interface thus constitutes a "proportional" controller, supplying heat on demand and having a temperature "offset"© from the equilibrium value if demand exists.…”

Section: Metal Freezing Pointsmentioning

confidence: 99%