___________________________________________________________________________ BURETTE DIFFERENCE OBSERVED DIFFERENCE CALCULATED READINGS WEIGHTS CORRECTION _______________ ______________ ______________ ______________ ______________ 0.02 16.27 10.12 10.10 26.35 10.08 -.02 20.09 9.97 36.26 9.91 -.06 30.16 10.07 46.34 10.08 +.01 40.19 10.03 56.31 9.97 -.06 50.00 9.81 66.17 9.86 +.05 _______________ ______________ ______________ ______________ ______________
These data to be obtained in duplicate for each burette.
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DETERMINATION OF COMPARATIVE STRENGTH HCl vs. NaOH
___________________________________________________________________________ DETERMINATION I II _________________________ ________________________ ________________________ Corrected Corrected Final Reading HCl 48.17 48.08 43.20 43.14 Initial Reading HCl 0.12 .12 .17 .17 ----- ----- ----- ----- 47.96 42.97 Corrected Corrected Final Reading HCl 46.36 46.29 40.51 40.37 Initial Reading HCl 1.75 1.75 .50 .50 ----- ----- ----- ----- 44.54 39.87 log cc. NaOH 1.6468 1.6008 colog cc. HCl 8.3192 8.3668 ------ ------ 9.9680 - 10 9.9676 - 10 1 cc. HCl .9290 cc. NaOH .9282 cc. NaOH Mean .9286 _________________________ ________________________ ________________________
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STANDARDIZATION OF HYDROCHLORIC ACID ===================================================================== Weight sample and tube 9.1793 8.1731 8.1731 6.9187 ------ ------ Weight sample 1.0062 1.2544 Final Reading HCl 39.97 39.83 49.90 49.77 Initial Reading HCl .00 .00 .04 .04 ----- ----- ----- ----- 39.83 49.73 Final Reading NaOH .26 .26 .67 .67 Initial Reading NaOH .12 .12 .36 .36 --- --- --- --- .14 .31 .14 .31 Corrected cc. HCl 39.83 - ----- = 39.68 49.73 - ----- = 49.40 .9286 .9286 log sample 0.0025 0.0983 colog cc 8.4014 - 10 8.3063 - 10 colog milli equivalent 1.2757 1.2757 ------ ------ 9.6796 - 10 9.6803 - 10 Normal value HCl .4782 .4789 Mean .4786 =====================================================================
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DETERMINATION OF CHLORINE IN CHLORIDE, SAMPLE No.
===================================================================== Weight sample and tube 16.1721 15.9976 15.9976 15.7117 ------- ------- Weight sample .1745 .2859 Weight crucible + precipitate 14.4496 15.6915 Constant weights 14.4487 15.6915 14.4485 Weight crucible 14.2216 15.3196 Constant weight 14.2216 15.3194 Weight AgCl .2269 .3721 log Cl 1.5496 1.5496 log weight AgCl 9.3558 - 10 9.5706 - 10 log 100 2.0000 2.0000 colog AgCl 7.8438 - 10 7.7438 - 10 colog sample 0.7583 0.5438 ------- ------- 1.5075 1.5078 Cl in sample No. 32.18% 32.20% =====================================================================
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STRENGTH OF REAGENTS
The concentrations given in this table are those suggested for use in the procedures described in the foregoing pages. It is obvious, however, that an exact adherence to these quantities is not essential.
Approx. Approx.
Grams relation relation per to normal to molal liter. solution solution
Ammonium oxalate, (NH_{4})_{2}C_{2}O_{4}.H_{2}O 40 0.5N 0.25 Barium chloride, BaCl_{2}.2H_{2}O 25 0.2N 0.1 Magnesium ammonium chloride (of MgCl_{2}) 71 1.5N 0.75 Mercuric chloride, HgCl_{2} 45 0.33N 0.66 Potassium hydroxide, KOH (sp. gr. 1.27) 480 Potassium thiocyanate, KSCN 5 0.05N 0.55 Silver nitrate, AgNO_{3} 21 0.125N 0.125 Sodium hydroxide, NaOH 100 2.5N 2.5 Sodium carbonate. Na_{2}CO_{3} 159 3N 1.5 Sodium phosphate, Na_{2}HPO_{4}.12H_{2}O 90 0.5N or 0.75N 0.25
Stannous chloride, SnCl_{2}, made by saturating hydrochloric acid (sp.
gr. 1.2) with tin, diluting with an equal volume of water, and adding a slight excess of acid from time to time. A strip of metallic tin is kept in the bottle.
A solution of ammonium molybdate is best prepared as follows: Stir 100 grams of molybdic acid (MoO_{3}) into 400 cc. of cold, distilled water. Add 80 cc. of concentrated ammonium hydroxide (sp. gr. 0.90).
Filter, and pour the filtrate slowly, with constant stirring, into a mixture of 400 cc. concentrated nitric acid (sp. gr. 1.42) and 600 cc. of water. Add to the mixture about 0.05 gram of microcosmic salt.
Filter, after allowing the whole to stand for 24 hours.
The following data regarding the common acids and aqueous ammonia are based upon percentages given in the Standard Tables of the Manufacturing Chemists' Association of the United States [!J.S.C.I.!, 24 (1905), 787-790]. All gravities are taken at 15.5C. and compared with water at the same temperature.
Aqueous ammonia (sp. gr. 0.96) contains 9.91 per cent NH_{3} by weight, and corresponds to a 5.6 N and 5.6 molal solution.
Aqueous ammonia (sp. gr. 0.90) contains 28.52 per cent NH_{3} by weight, and corresponds to a 5.6 N and 5.6 molal solution.
Hydrochloric acid (sp. gr. 1.12) contains 23.81 per cent HCl by weight, and corresponds to a 7.3 N and 7.3 molal solution.
Hydrochloric acid (sp. gr. 1.20) contains 39.80 per cent HCl by weight, and corresponds to a 13.1 N and 13.1 molal solution.
Nitric acid (sp. gr. 1.20) contains 32.25 per cent HNO_{3} by weight, and corresponds to a 6.1 N and 6.1 molal solution:
Nitric acid (sp. gr. 1.42) contains 69.96 per cent HNO_{3} by weight, and corresponds to a 15.8 N and 15.8 molal solution.
Sulphuric acid (sp. gr. 1.8354) contains 93.19 per cent H_{2}SO_{4} by weight, and corresponds to a 34.8 N or 17.4 molal solution.
Sulphuric acid (sp. gr. 1.18) contains 24.74 per cent H_{2}SO_{4} by weight, and corresponds to a 5.9 N or 2.95 molal solution.
The term !normal! (N), as used above, has the same significance as in volumetric analyses. The molal solution is assumed to contain one molecular weight in grams in a liter of solution.
DENSITIES AND VOLUMES OF WATER AT TEMPERATURES FROM 15-30C.
Temperature Density. Volume.
Centigrade.
4 1.000000 1.000000 15 0.999126 1.000874 16 0.998970 1.001031 17 0.998801 1.001200 18 0.998622 1.001380 19 0.998432 1.001571 20 0.998230 1.001773 21 0.998019 1.001985 22 0.997797 1.002208 23 0.997565 1.002441 24 0.997323 1.002685 25 0.997071 1.002938 26 0.996810 1.003201 27 0.996539 1.003473 28 0.996259 1.003755 29 0.995971 1.004046 30 0.995673 1.004346
Authority: Landolt, Bornstein, and Meyerhoffer's !Tabellen!, third edition.
CORRECTIONS FOR CHANGE OF TEMPERATURE OF STANDARD SOLUTIONS
The values below are average values computed from data relating to a considerable number of solutions. They are sufficiently accurate for use in chemical analyses, except in the comparatively few cases where the highest attainable accuracy is demanded in chemical investigations. The expansion coefficients should then be carefully determined for the solutions employed. For a compilation of the existing data, consult Landolt, Bornstein, and Meyerhoffer's !Tabellen!, third edition.
Corrections for 1 cc.
Concentration. of solution between 15 and 35C.
Normal .00029 0.5 Normal .00025 0.1 Normal or more dilute solutions .00020
The volume of solution used should be multiplied by the values given, and that product multiplied by the number of degrees which the temperature of the solution varies from the standard temperature selected for the laboratory. The total correction thus found is subtracted from the observed burette reading if the temperature is higher than the standard, or added, if it is lower. Corrections are not usually necessary for variations of temperature of 2C. or less.
INTERNATIONAL ATOMIC WEIGHTS
========================================================== 1920 1920 _________________ _________ ___________________ __________ Aluminium Al 27.1 Molybdenum Mo 96.0 Antimony Sb 120.2 Neodymium Nd 144.3 Argon A 39.9 Neon Ne 20.2 Arsenic As 74.96 Nickel Ni 58.68 Barium Ba 137.37 Nitrogen N 14.008 Bismuth Bi 208.0 Osmium Os 190.9 Boron B 11.0 Oxygen O 16.00 Bromine Br 79.92 Palladium Pd 106.7 Cadmium Cd 112.40 Phosphorus P 31.04 Caesium Cs 132.81 Platinum Pt 195.2 Calcium Ca 40.07 Potassium K 39.10 Carbon C 12.005 Praseodymium Pr 140.9 Cerium Ce 140.25 Radium Ra 226.0 Chlorine Cl 35.46 Rhodium Rh 102.9 Chromium Cr 52.0 Rubidium Rb 85.45 Cobalt Co 58.97 Ruthenium Ru 101.7 Columbium Cb 93.1 Samarium Sm 150.4 Copper Cu 63.57 Scandium Sc 44.1 Dysprosium Dy 162.5 Selenium Se 79.2 Erbium Er 167.7 Silicon Si 28.3 Europium Eu 152.0 Silver Ag 107.88 Fluorine Fl 19.0 Sodium Na 23.00 Gadolinium Gd 157.3 Strontium Sr 87.63 Gallium Ga 69.9 Sulphur S 32.06 Germanium Ge 72.5 Tantalum Ta 181.5 Glucinum Gl 9.1 Tellurium Te 127.5 Gold Au 197.2 Terbium Tb 159.2 Helium He 4.00 Thallium Tl 204.0 Hydrogen H 1.008 Thorium Th 232.4 Indium In 114.8 Thulium Tm 168.5 Iodine I 126.92 Tin Sn 118.7 Iridium Ir 193.1 Titanium Ti 48.1 Iron Fe 55.84 Tungsten W 184.0 Krypton Kr 82.92 Uranium U 238.2 Lanthanum La 139.0 Vanadium V 51.0 Lead Pb 207.2 Xenon Xe 130.2 Lithium Li 6.94 Ytterbium Yb 173.5 Lutecium Lu 175.0 Yttrium Y 88.7 Magnesium Mg 24.32 Zinc Zn 65.37 Manganese Mn 54.93 Zirconium Zr 90.6 Mercury Hg 200.6 ==========================================================