1、Designation: D1016 05 (Reapproved 2015)Standard Test Method forPurity of Hydrocarbons from Freezing Points1This standard is issued under the fixed designation D1016; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the sampling and determinationof purity of essentially pure compounds for which the freezingpoints
3、for zero impurity and cryoscopic constants are given.2The compounds to which the test method is applicable are:(WarningExtremely flammable liquids and liquefied gases.)n-butane 1,3-butadieneisobutane isoprene(2-methyl-1,3-butadiene)n-pentane benzeneisopentane toluene (methylbenzene)n-hexane ethylben
4、zenen-heptane o-xylene (1,2-dimethylbenzene)n-octane m-xylene (1,3-dimethylbenzene)2,2,4-trimethylpentane p-xylene (1,4-dimethylbenzene)methylcyclohexane styrene (ethenylbenzene)isobutene1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for informatio
5、n only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For spe
6、cific hazardstatements, see Sections 1, 6, 8, and 1026.NOTE 1This test method covers systems in which the impurities formwith the major component a substantially ideal or sufficiently dilutesolution, and also systems which deviate from the ideal laws, providedthat, in the latter case, the lowering o
7、f the freezing point as a function ofthe concentration is known for each most probable impurity in the givensubstance.2. Referenced Documents2.1 ASTM Standards:3D1015 Test Method for Freezing Points of High-PurityHydrocarbons3. Summary of Test Method3.1 After measurement of the freezing point of the
8、 actualsample, purity can be calculated from the value of thedetermined freezing point and the values given for the freezingpoint for zero impurity and for the applicable cryoscopicconstant or constants.43.2 For the equilibrium between an infinitesimal amount ofthe crystalline phase of the major com
9、ponent and a liquid phaseof the major component and one or more other components, thethermodynamic relation between the temperature of equilib-rium and the composition of the liquid phase is expressed bythe equation:521n N1521n1 2 N2! 5 Atf 02 tf!11Btf 02 tf!1#(1)where:N1= mole fraction of the major
10、 component,N2=(1N1) = sum of the mole fractions of all the othercomponents,tf= freezing point, in degrees Celsius, of the given sub-stance (in which the mole fraction of the majorcomponent is N1), defined as the temperature at whichan infinitesimal amount of crystals of the majorcomponent is in ther
11、modynamic equilibrium with theliquid phase (see Note 3 of Test Method D1015),tf0= freezing point for zero impurity, in degrees Celsius, forthe major component when pure, that is, when N1=1or N2=0,1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, an
12、d Lubricants and is the direct responsibility ofSubcommittee D02.04.0D on Physical and Chemical Methods.Current edition approved April 1, 2015. Published May 2015. Originallyapproved in 1949. Last previous edition approved in 2010 as D1016 05 (2010).DOI: 10.1520/D1016-05R15.2Numerical constants in t
13、his test method were taken from the most recentlypublished data appearing in “Tables of Physical and Thermodynamic Properties ofHydrocarbons and Related Compounds,” or ASTM DS 4A, Physical Constants ofHydrocarbons C1to C10, or both, prepared by the American Petroleum Institute,Research Project 44.3F
14、or referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4For a more complete discussion of this test method, see Glasgo
15、w, A. R., Jr.,Streiff, A. J., and Rossini, F. D., “Determination of the Purity of Hydrocarbons byMeasurement of Freezing Points,” Journal of Research , JRNBA, National Instituteof Standards and Technology, Vol 35, No. 6, 1945, p. 355.5For details, see Taylor, W. J., and Rossini, F. D., “Theoretical
16、Analysis ofTime-Temperature Freezing and Melting Curves as Applied to Hydrocarbons,”Journal of Research, JRNBA, Nat. Bureau Standards, Vol 32, No. 5, 1944, p. 197;also Lewis, G. N., and Randall, M., “Thermodynamics and the Free Energy ofChemical Substances,” 1923, pp. 237, 238, McGraw-Hill Book Co.,
17、 New York, NY.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1A = first or main cryoscopic constant, in mole fraction perdegree, andB = secondary cryoscopic constant, in mole fraction perdegree.Neglecting the higher terms not written
18、in the brackets, Eq 1can be transformed to the equation:log10P 5 2.00000 2 A/2.3026!tf 02 tf!11Btf 02 tf!#(2)where:P = purity of the given substance in terms of mole percent ofthe major component.4. Significance and Use4.1 The experimental procedures and physical constantsprovided by this test metho
19、d, when used in conjunction withTest Method D1015, allow the determination of the purity ofthe material under test. A knowledge of the purity of thesehydrocarbons is often needed to help control their manufactureand to determine their suitability for use as reagent chemicalsor for conversion to othe
20、r chemical intermediates or finishedproducts.5. Apparatus5.1 Sampling Apparatus, as shown in Fig. 1, for withdraw-ing liquefied gases (for example, 1,3-butadiene) from pressurestorage cylinders.5.2 Distilling Apparatus, as shown in Fig. 2, for removingsmall amounts of polymer from low-boiling compou
21、nds (forexample, 1,3-butadiene) by simple distillation at atmosphericpressure.5.3 Distilling Apparatus, as shown in Fig. 3, for removingsmall amounts of polymer from compounds with boiling pointsnear room temperature (for example, isoprene) by distillationat atmospheric pressure.5.4 Vacuum Distillin
22、g Apparatus and Transfer Trap, asshown in Fig. 4, for removing dissolved air and large amountsof polymer from a compound (for example, 1,3-butadiene orstyrene), by repeated freezing and evacuation, followed bydistillation of the compound in vacuum in a closed system.6. Materials6.1 Carbon Dioxide Re
23、frigerantSolid carbon dioxide in asuitable liquid. (WarningExtremely cold (78.5 C). Liber-ates heavy gas which can cause suffocation. Contact with skincauses burns or freezing, or both. Vapors can react violentlywith hot magnesium or aluminum alloys.) Acetone is recom-mended. (WarningExtremely flamm
24、able. Harmful if in-haled. High concentrations can cause unconsciousness ordeath. Contact can cause skin irritation and dermatitis. Userefrigerant bath only with adequate ventilation!)6.2 Liquid Nitrogen or Liquid Air(WarningExtremelycold. Liberates gas which can cause suffocation. Contact withskin
25、causes burns or freezing, or both. Vapors can reactviolently with hot magnesium or aluminum alloys.) For use asa refrigerant. If obtainable, liquid nitrogen is preferable be-cause of its safety.6.2.1 Use liquid nitrogen refrigerant only with adequateventilation. If liquid air is used as a refrigeran
26、t, it is imperativethat any glass vessel containing hydrocarbon or other combus-tible compound and immersed in liquid air be protected with asuitable metal shield. The mixing of a hydrocarbon or othercombustible compound with liquid air due to the breaking of aglass container would almost certainly
27、result in a violentexplosion. If liquid nitrogen is used as a refrigerant, nohydrocarbon sample should ever be permitted to cool below thecondensation temperature of oxygen (183 C at atm). Thiswould not be likely to occur in normal operation, but mightoccur if the apparatus were left unattended for
28、some time.7. Procedure7.1 Measure the freezing point as described in Test MethodD1015, using the modifications and constants given in Sections826of this test method for the specific compounds beingexamined.NOTE 2The estimated uncertainty in the calculated value of the purityas referred to in Section
29、s 826is not equivalent to the precision definedin RR:D02-1007.8. n-Butane6(WarningExtremely flammable liquefiedgas under pressure. Vapor reduces oxygen available forbreathing.)8.1 Determine the freezing point from freezing curves, withthe cage stirrer, with a cooling bath of liquid nitrogen (or liqu
30、idair), with a cooling rate of 0.3 Cmin to 0.8 Cmin for theliquid near the freezing point, and with crystallization inducedimmediately below the freezing point by means of a cold rod.8.2 The method of obtaining the samples shall be asfollows: Assemble the apparatus for obtaining the sample asshown i
31、n Fig. 1, but with no lubricant on the ground-glassjoints and with the valve at the bottom of the cylinder, so thatsampling is from the liquid phase. Attach to C an absorptiontube containing anhydrous calcium sulfate or other suitabledesiccant (except magnesium perchlorate) so that water is notintro
32、duced into the system (Note 3). Fill the flask F with thecarbon dioxide refrigerant to within about 51 mm (2 in.) of thetop. After about 20 min or 30 min, when the system will havecooled sufficiently, remove the absorption tube and begin thecollection of liquid n-butane by opening the valve K andadj
33、usting the needle valve J so that the sample is collected ata rate of 1 mL to 2 mL (liquid)/min in the condensing tube E.NOTE 3However, if some water does condense with the hydrocarbon,the freezing point will not be affected significantly because of theextremely low solubility of water in the hydroc
34、arbon at the freezing pointof the latter.8.3 Assemble the freezing point apparatus. Place the cool-ing bath in position around the freezing tube (O in Fig. 1 ofTest Method D1015), letting the temperature as read on theplatinum thermometer reach about 80 C when all the samplehas been collected.6For f
35、urther details, see Glasgow , A. R., Jr., et al. “Determination of Purity byMeasurement of Freezing Points of Compounds Involved in the Production ofSynthetic Rubber,” Analytical Chemistry, ANCHA, Vol 20, 1948, p. 410.D1016 05 (2015)28.4 When 50 mL of liquid (temperature about 80 C) hasbeen collecte
36、d in the condensing tube, close the valve K (Fig.1) and allow the liquid which has collected at I to warm andtransfer to the condensing tube (Note 4). Replace the attachingtubes G and D on the condensing tube by caps. The liquidsample is now ready for introduction into the freezing tube (Oin Fig. 1
37、of Test Method D1015).NOTE 4In case the original sample contained water, there will remainat I some water that may be discarded after the hydrocarbon portion hasbeen collected as outlined above.8.5 When the temperature of the platinum thermometer isnear 80 C, remove the condensing tube (E in Fig. 1)
38、 from theDewar flask. Wrap a cloth around the upper portion of thecondensing tube (for ease of handling and for preventing therefrigerating liquid from contaminating the sample onpouring), and after removing the caps on the condensing tube,raise the stopper holding the platinum thermometer, and pour
39、the sample through the tapered male outlet of the condensingtube into the freezing tube (O in Fig. 1 of Test Method D1015).Quickly replace the stopper holding the platinum thermometer,AThree-way T stopcock, borosilicate glass (similar to Corning Pyrex No. 7420).BConnection to vacuum for purging and
40、for evacuating system CDEGHI.CCapillary tube for venting, to which drying tube is also connected.DJoint, standard taper, 12/30, borosilicate glass.ECondensing tube, borosilicate glass.FDewar flask, 1 qt size, borosilicate glass (similar to American Thermos Bottle Co. No. 8645).GTubing, borosilicate
41、glass, 10 mm in outside diameter, with spherical ground-glass joints, 18/7.HTubing, silicate glass, 10 mm in outside diameter, with spherical ground-glass joints, 18/7.IMetal connection, brass spherical male joint at one end fitting to connection to needle valve at other end.JNeedle valve, brass.KVa
42、lve on cylinder containing hydrocarbon material.LStandard cylinder containing hydrocarbon material.MFitting to connect needle valve J to valve K on cylinder.FIG. 1 Apparatus for Obtaining SampleD1016 05 (2015)3and start the stirrer, with dry air flowing into the upper portionof the freezing tube thr
43、ough M (Fig. 1 of Test Method D1015).8.6 Because the material is normally gaseous at roomtemperature, care should be taken in disposing of the samplesafely.8.7 For n-butane, the freezing point for zero impurity, in airat 1 atm, is as follows:tf 052138.362 C60.025 C (3)and the cryoscopic constants ar
44、e:A 5 0.03085 mole fraction/C and (4)B 5 0.0048 mole fraction/C. (5)8.8 The cryoscopic constants given in 8.7 are applicable tosamples of n-butane having a purity of about 95 mole % orbetter, with no one impurity present in an amount that exceedsits eutectic composition with the major component.8.9
45、The estimated uncertainty in the calculated value of thepurity is as follows, in mole %:Calculated Purity,mole %Uncertainty, plus orminus, mole %Over 99.5 0.0899.0 to 99.5 0.0998 to 99 0.1097 to 98 0.1296 to 97 0.1595 to 96 0.209. Isobutane6(WarningExtremely flammable gas underpressure. Vapor reduce
46、s oxygen available for breathing.)9.1 Determine the freezing point from freezing curves withthe cage stirrer, with a cooling bath of liquid nitrogen (or liquidair), with a cooling rate of 0.3 Cmin to 0.8 Cmin for theliquid near the freezing point, and with crystallization inducedimmediately below th
47、e freezing point by means of a cold rod.9.2 Obtain the samples as follows: Assemble the apparatusfor obtaining the sample as shown in Fig. 1, but with nolubricant on the ground-glass joints and with the valve at thebottom of the cylinder, so that sampling is from the liquidphase. Attach to C an abso
48、rption tube containing anhydrouscalcium sulfate or other suitable desiccant (except magnesiumperchlorate) so that water is not introduced into the system(Note 3). Fill the flask F with the carbon dioxide refrigerant towithin about 51 mm (2 in.) of the top. After about 20 min or30 min, when the syste
49、m will have cooled sufficiently, removethe absorption tube and begin the collection of liquid isobutaneby opening the valve K and adjusting the needle valve J so thatthe sample is collected at a rate of 1 mL to 2 mL (liquid)/minin the condensing tube E.9.3 Assemble the freezing point apparatus. Place the cool-ing bath in position around the freezing tube (O in Fig. 1 ofCDewar vessel, 1 qt capacity, borosilicate glass.DClamp.EDistilling tube, borosilicate glass, 25 mm in outside diameter.FStandard-taper ground-glass jo
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