T H E J O U R N A L OF I,VDUSTRIAL A N D ENGINEERING C H E M I S T R Y
Apr.1 1919
STANDARD ALKALI FOR MIXED ACID CONTROL By
EVELYNHEARSEYAND C.
M . JOYCE
Received August 15, 1918
S t a n d a r d alkali for t h e titration of mixed acids usually consists of normal sodium hydroxide s t s n d ardiaed through normal sulfuric acid, standardized in t u r n b y sodium carbonate with methyl orange as a n indicator. This procedure has several disadvantages, which are discussed i n t h e (‘Standardization of Alkalimetric Solutions,” b y Francis D. Dodge,l who recommends potassium acid phthalate as a standard. T h e accuracy of this method has been established b y W. S. Hendrixson i n his careful experimental s t u d y of t h e subject.2 T h e advantages of direct standardization with potassium acid phthalate over titration with normal acid which m u s t b e standardized b y a troublesome process, are so obvious t h a t it seems strange t h a t t h e new method has not come into more widespread use. T h e reason may be contained in t h e fact t h a t phenolphthalein, in spite of its sensitiveness, is not a s desirable an indicator as methyl orange when carbonates are present in t h e s t a n d a r d alkali. B y following t h e procedure described in “Preparation of a Solution for Ma,king S t a n d a r d Solutions of Sodium Hydroxide,”3 t h e interference of carbonates with t h e indicator can be easily eliminated. A s t a n d a r d solution prepared in t h i s manner m a y be titrated against potassium acid phthalate in t h e cold using phenolphthalein as a n indicator. A standardization along these lines, performed in 1
THISJOURNAL, 7 (1913,
*
J . A m . Chem. Soc., 37 (1915), 2352. Cowles, I b i d . , 30 (19081, 1192.
29.
341
this laboratory, differed from t h e result of a titration against N / 5 acid standardized with sodium carbonate b y less t h a n 0 . o 5 per cent. STANDARDIZATION OF N / 5 wit,
KHC8HaOl Grams 1.750 I ,754 1.743 1,741
HYDROXIDE WITH ACID POTASSIUM PHTHhLATE Vol. N / 5 NaOH Equivalent NaOH(a) t o 1 g . KHCeHaO4 X N/5 Grams cc. cc. 42.81 24.49 X 1.750 i42.81 = 1.001 42.95 24.49 X 1.754 + 42.95 = 1,000 42.66 24.49 X 1.753 -+ 42.66 = 1.001 42.61 24.49 X 1.741 -+ 42.61 = 1.001 SODIUM
AVERAGE,1,001 STANDARDIZATION O F N / S SULFURIC ACID WITH SODIUMCARBONATE Wt. Vol. N / S HzSO~ Equivalent NaaC03 HzSOc(a) t o 1 g . NazCOs x n/s cc. c c. Gram Gram 47.44 94.33 X 0.5000 0.5000 + 47.44 = 0.9942 47.49 94.33 X 0 . 5 0 0 5 + 47.49 = 0.9942 0.5005 47.41 94.33 0.4995 X 0.4995 + 47.41 = 0.9939 47.40
0.4995
94.33
X 0.4995 f 47.40 = 0.9941
-
AVERAGE, 0.9941
N / S SULFURIC ACID vs. N / 5 SODIUMHYDROXIDE N / 5 HzSOa(o) X N/5 N / 5 NaOH cc. Gram cc. N / 5 NaOH X X X X
42.33 42.45 42.34 42.33
0.9941 0.9941 0.9941 0.9941
-:
f
-: -:
42.03 42.15 42.05 42.05
= = = =
1.001 1.001 1.001 1.001
.... 1.001
AVERAGE
( a ) Corrected for calibration, temperature, and run back.
These d a t a were obtained in connection with ordinary control work a n d without unusual precautions, except t h a t all t h e burettes used for alkali were freshly calibrated as t h e y change appreciably every few months from solvent action. T h e potassium acid p h t h a l a t e used was prepared from Merck’s phthalic anhydride b y Dodge’s meth0d.l T h e sodium carbonate used was Kahlbaum’s “for analysis.” LEOMINST~R, MASSACHUSETTS 1
LOG.
cit.
ADDRESSES AND CONTRIBUTED ARTICLES OUR OPPORTUNITY By BERNHARD C. HESSE~
Since the early days of the war, exhortations to cooperation as a remedy-in fact the only remedy-for the then suddenly revealed, although long known, lack of self-containedness and of xndustrial independence in many countries and especially in what have since been grouped as “key” or “pivotal” industries have been numerous, widespread, and persistent. Our own country and our own business and profession have by no means escaped those exhortations. In fact, our profession has been made the special target for unfounded, vehement, and indiscriminate charges of inexcusable backwardness in development and of conspicuous want of courage in operation and expansion; in corresponding measure we have been urged and have ourselves repeatedly promised cooperation as a cure for those alleged conditions. While the war was on, all our industries bent all their energies towards accomplishing the heavy tasks imposed upon them in the shortest possible time, regardless of any and all refinements as to efficiency and exquisiteness of workmanship. Consideration of measures of development or of cooperation to be followed upon the return of peace had to be put to one side until the imniediate and pressing war needs were out of the way. With the signing of the armistice opportunity for such consideration 1
Read before the Lehigh Valley Section, American Chemical Society,
at Easton, P a , , March 14, 1919.
CHEMIcame measurably closer. The Council of the AMERICAN CAL SOCIETY then took immediate steps to formulate a cooperative policy for after-the-war conditions. THE CHEMIST IN THE LIFE O F THE NATION
Before discussing our opportunity it will be serviceable to review what the probable general position of our business and profession is in the national economic life of our country. Those who follow chemical pursuits of whatever kind in this country made up, before the war, I/IOOOO of our population; those of us then engaged in industrial activities, as distinguished from educational and like activities, were engaged in industries which employed 1/6 of the industrial wage-earners of the country, produced 1/4 of the value of all manufactures in the country, created r / 5 of the total value created by manufacture in this country, in their trade with one Eoreign country alone made up 1/20 of our total foreign business and produced 117 of our balance of trade. The forthcoming census will, no doubt, show a decided growth of our importance, both relative and actual, in our national economic life. RECIPROCAL RESPONSIBILITIES
Bulking so large in the economic life of our country as do the industrial activities of this I/IOOOO of the country’s population it is clear on the one hand that the nation owes it to itself to see to it that the activities of this I/IOOOO are interfered with as little as possible and are enhanced to the utmost, and on the
