850
INDUSTRIAL AND ENGISEERING CHEMISTRY
Vol. 15, S o . 8
T h e Viscosities of Mixtures of Sulfuric Acid and Water' By F. H. Rhodes and C. B. Barbour CORNELLUNIVERSITY,
ITHACA,
N. Y .
T
HE viscosities of This investigation was undertaken for the purpose of verifging the eating the temperature of results of preoious work on the oiscosities of mixtures of suQuric the liquid within the bulb mixtures of sulfuric acid and water have acid and water. The procedure for the determination is described and the glass rod which been determined by Graand the results are shown both in tabular and graphic form. The served as the stem of the results are compared with those of earlier inoestigators. and a discut-off valve at the bottom ham,' 1vagner,3 and Duncussion. of the practical application of these resutls is included. of the bulb. The viscomstan and Wilson.4 The measurements made by eter was supported, as shown, in an inverted bell Graham were a t a single temperature only (20" C.), while the determinations by jar, which served as a constant temperature water jacket, the Dunstan and Wilson were all made at 25" C. Wagner deter- apparatus being so arranged that both the bulb and the capilmined the viscosities a t temperatures of 15", 25", 35", and lary were maintained a t the temperature of the water within 45" C., but he used only three mixtures, containing, respec- the bath. The water in the water bath was heated by live steam, when necessary, and was stirred by a slow current of air. tively, 23.4, 15.5, and 7.87 per cent of sulfuric acid. In making a determination of viscosity, the liquid to be Obviously, the results obtained by these earlier investigators give little information as to the effect of temperature tested and the water in the water bath were heated separately upon the viscosities of solutions of sulfuric acid. Moreover, to the temperature at which the determination was to be these earlier results made. The liquid was then placed in the viscometer bulb, do not agree very and both the liquid in the bulb and the water in the water well among them- bath were brought to the desired temperature and mainselves. The values tained at this temperature throughout the determination. obtained by Dunstan When the temperature was adjusted properly, the valve was and Wilson are very lifted and liquid was allowed to flow from the bulb until the much higher than capillary was filled and the meniscus at the top of the liquid those given by Wag- stood exactly at the level indicated by a fixed mark around ner for solutions of the bulb. A graduated flask, containing exactly 63.6 cc., was similar concentra- then placed below the capillary, the valve was lifted to a tions and at the same definite height, and the time required for the outflow of temperature. Gra- exactly 63.3 cc. of the liquid was determined. The viscometer was calibrated by determining the times ham and also Dunstan and Wilson ob- of flow of several liquids of known kinematic viscosity, and served a maximum from these results a calibration curve for the instrument mas in the viscosity-con- drawn (Fig. 2 ) . The liquids used in calibrating the viscentration curve a t a cometer were water, benzene, linseed oil, 20 per cent sucrose point corresponding solution, 40 per cent sucrose solution, and various petroleum to the composition of oils. The values for the viscosities of benzene and of linthe hydrate H2S04.- seed oil were taken from the Smithsonian Tables, those for HzO; but Dunstan the viscosities of water and the sucrose solutions were those and Wilson observed ,oo a minimum in the 80 curve between this a point and the point corresponding to the composition of pure H2S04,while Graham obserded no such FIG. 1 -VISCOMETER FOR DETERMINATION OF ~ 1 s c o s I T I E s on M I X T U R E S on SULFURIC minimum. ACID AND W A T E R
EXPERIMENTAL The viscometer used in this work consisted of a cylindrical glass bulb with a capacity of about 200 cc., provided with a tubulature a t the top and terminating a t the bottom in a glass capillary tube which was 8 cm. long and 1 mm. in internal diameter. A glass valve, mounted on a glass rod, was ground in to close the passage between the bulb and the lower capillary tube. The upper tubulature was fitted with a cork stopper which was provided with an air vent, through which were inserted the thermometer for indi-
* Received March 26, 1923. * Graham, Trans. R o y . SOC.London, 16lA,373 (1861). 8
4
Wagner, A n n . Physik, 18, 259 (1883). Dunstan and Wilson, J . Chem. SOC.(London), 91, 83T (1907).
FIG.2 -CALIBRATIONCURVE
INDUSTRIAL AND ENGINEERING CHEMISTRY
August, 1923
851
65 60
55 50
45
40 35 3L
25 2L 15
I
0.250
' o.200
0*'50 6.0
6.5
7.0
7.5
8.0
8.5
