ASTM D3444-2000(2005) Standard Test Method for Total Acid Number of Trichlorotrifluoroethane《三氯三氟乙烷的酸度总值的标准试验方法》.pdf

1、Designation: D 3444 00 (Reapproved 2005)Standard Test Method forTotal Acid Number of Trichlorotrifluoroethane1This standard is issued under the fixed designation D 3444; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l

2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of totalacidity in trichlorotrifluoroethane and other halocarbons thatare li

3、quid at room temperature.1.2 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 pri

4、or to use. Specific precau-tionary statements are given in Section 6.2. Summary of Test Method2.1 The total acidity of the solvent is determined by titrationwith standard alcoholic potassium hydroxide solution usingphenolphthalein solution as the indicator.3. Significance and Use3.1 This test method

5、 determines the total acidity of trichlo-rotrifluoroethane by titration with alcoholic potassium hydrox-ide using phenolphthalein for an indicator.3.2 This test method can be used to develop production andpurchasing specifications.4. Apparatus4.1 Buret, 2-mL in 0.01-mL subdivisions, self-leveling, w

6、ith1000-mL reservoir.4.2 Vinyl Tubing.24.3 Two Indicating Carbon Dioxide Absorbent Tubes, 3050mesh.5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on

7、Analytical Reagents of the American Chem-ical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless other

8、wise indicated, referencesto water shall be understood to mean halide-free distilled water.5.3 Isopropyl Alcohol.5.4 Phenolphthalein Indicator Solution (0.05 g in 100 mLof isopropyl alcohol).5.5 Potassium Acid Phthalate, U.S. National Bureau ofStandards primary standard. Dry this chemical in a 120C

9、ovenfor several hours prior to use. Store the dry chemical in adesiccator.5.6 Potassium Hydroxide Pellets.5.7 Potassium Hydroxide Solution in Isopropyl Alcohol(0.01 N)Add approximately1gofsolid KOH to approxi-mately 1 L of anhydrous isopropyl alcohol in a 2-L Erlenmeyerflask. Boil the mixture gently

10、 for 5 to 10 min, stirring toprevent the solids from forming a cake on the bottom. Add atleast 2 g of barium hydroxide Ba(OH)2 and boil again gentlyfor 5 to 10 min. Cool to room temperature. Allow to stand forseveral hours and filter the supernatant liquid through a finesintered glass or porcelain f

11、iltering funnel. Avoid unnecessaryexposure to CO2during filtration. Store the solution out ofcontact with cork or rubber. Protect the solution from CO2bya guard tube containing Ascarite II.4Standardize against purepotassium acid phthalate in about 25 mL of CO2-free waterusing phenolphthalein to dete

12、ct the end point.6. Hazards6.1 Trichlorotrifluoroethane removes natural oils from skin.Avoid skin contact. The solvent is not flammable and has athreshold limit value of 1000 ppm by volume in air. See themanufacturers MSDS.1This test method is under the jurisdiction of ASTM Committee D26 onHalogenat

13、ed Organic Solvents and Fire Extinguishing Agents and is the directresponsibility of Subcommittee D26.04 on Test Methods.Current edition approved June 1, 2005. Published June 2005. Originallyapproved in 1975. Last previous edition approved in 2000 as D 3444 00.2Tygon has been found satisfactory. An

14、equivalent may be used.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the U

15、nited States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4Ascarite II has been found satisfactory and is available from chemical supplyhouses.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United S

16、tates.6.2 Isopropyl alcohol is flammable, and has a thresholdlimit value of 400 ppm by volume in air. See the manufactur-ers MSDS.6.3 Potassium hydroxide is corrosive to body tissue. Avoidcontact with the solid and its solution. Should this chemicalcontact the person, immediately flush the affected

17、area withcopious amounts of water. See the manufacturers MSDS.7. Procedure7.1 For sample analysis, add 50 mL of isopropyl alcohol toa 250-ml Erlenmeyer flask, add 5 drops of phenolphthaleinindicator solution and titrate to a pink end point with alcoholicKOH solution.7.1.1 Swirl flask contents gently

18、 during titration. The endpoint should last for 10 to 15 s. Stopper the flask until thesample is added to minimize CO2contamination.7.2 Pour a weighed sample (about 50.00 6 0.02 g) into theflask containing the pretitrated alcohol.7.3 Titrate the sample with the standard alcoholic KOHsolution to a 15

19、-s pink end point. Record the amount of titrantrequired.7.4 For standardization of 0.01 N KOH in isopropyl alcohol,proceed as follows:7.4.1 Weigh (60.0001 g) 0.142 6 0.005 g of dry (NationalBureau of Standards) primary standard potassium acid phtha-late into a 1-L volumetric flask containing about 5

20、00 mL ofdeionized CO2-free water, then stopper the flask.7.4.2 Swirl the flask to dissolve the potassium acid phtha-late.7.4.3 Fill the flask to volume with deionized, CO2-freewater, stopper the flask then mix the solution thoroughly.7.4.4 Place 25 mL (transfer pipet) of deionized, CO2-freewater and

21、 5 drops of phenolphthalein indicator solution into a250-mL Erlenmeyer flask.7.4.5 Pipet 25 mL (transfer pipet) of the potassium acidphthalate standard solution into the flask, then seal the flaskwith a stopper.57.4.6 Treat the blank and standard alike from this point on.7.4.7 Titrate the standard w

22、ith the approximate 0.01 Npotassium hydroxide solution to the phenolphthalein indicatorend point. Record the titer.8. Calculation8.1 Calculate the acid number of the solvent as follows:Total acid number in 1 mg of KOH/g sample5 A 3 N 3 56.1!/Wwhere:A = millilitres of KOH solution required for titrat

23、ion ofsample, mL,N = normality of KOH solution, andW = weight of sample, g.8.2 Calculate the normality of the potassium hydroxidestandard as follows:N, KOH 5 G3 V!/204.224 3 A 2 B!# (1)where:A = standard titer, mL,B = blank titer, mL,G = potassium acid phthalate, g,V = potassium acid phthalate aliqu

24、ot, mL, and204.224 = potassium acid phthalate/mole, g.8.3 Average the normality values obtained from triplicateanalyses to the nearest 0.0001 unit. Use the average normalityfor sample calculation.9. Precision and Bias69.1 Repeatability (Single Analyst): At a mean value of0.0018 mg-KOH/g the standard

25、 deviation of results (each theaverage of triplicates obtained by the same analyst on twodifferent days) has been estimated to be 0.0010 mg-KOH/g atthree degrees of freedom. Two such values should be consid-ered suspect (95 % confidence level) if they differ by more than0.0045 mg-KOH/g.9.2 Reproduci

26、bility (Multilaboratory): At a mean value of0.0018 mg-KOH/g the standard deviation of results (each theaverage of triplicates in three different laboratories), obtainedby analysts in different laboratories, has been estimated to be0.0036 mg-KOH/g at two degrees of freedom. Two such valuesshould be c

27、onsidered suspect (95 % confidence level) if theydiffer by more than 0.0219 mg-KOH/g.10. Keywords10.1 acidity; CFC-113; total acid number;trichlorotrifluoroethaneASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this st

28、andard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be rev

29、iewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsi

30、ble technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West C

31、onshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).5Neoprene has been found satisfactory. An equivalent may be used.6Supporting data are available from ASTM Headquarters. Request RR: D26-1011.D 3444 00 (2005)2