October 1955
INDUSTRIAL AND ENGINEERING CHEMISTRY
pressure ( 7 ) with critically chosen values of specific weight, with a probable error of less than 0.05%. MATERIALS
The n-heptane was purchased as research grade from the Phillips Petroleum Co. and was reported to contain 0.0006 mole fraction of impurities. It was fractionated once a t reduced pressure in a column containing 16 glass plates a t a reflux ratio greater than 20. The first and last 10% of the overhead was discarded. After passage of the liquid through activated alumina and deaeration by prolonged refluxing a t reduced pressure, it was dried over metallic sodium. The specific weight of the sample of n-heptane a t 77’ F. was 42.4232 pounds per cubic foot, which compared with 42.4195 pounds per cubic foot reported by Rossini for an air-saturated sample a t the same temperature. The index of refraction for the deaerated sample relative to the D-lines of sodium was 1.3853 as compared to a value of 1.3851 reported by Rossini for an air-saturated sample. A comparison of these data indicates that the sample employed for these measurements probably contained less than 0.0005 mole fraction of material other than n-heptane. I t is believed that the impurities are primarily isomeric hydrocarbons. EXPERIMENTAL RESULTS
The measurements of the volumetric behavior of n-heptane are given in Table I. No results were reported for the two-phase region, since the vapor pressure was already well established ( 1 , 7 , 10). The experimental results are depicted in Figure 1. The standard deviation of the experimental points from the smoothed curve was 0.0016 cubic foot per pound-mole Smoothed values of the molal volume of n-heptane for each of the temperatures investigated are recorded in Table 11. The bubble point pressures included in this table were taken from the critically chosen values of Rossini ( 7 ) a t the lowe. temperatures and the measurements of Beattie ( 1 , IO) a t the higher temperatu-es. The deviation of Beattie’s volumetric measurements from the present investigation is shown in Figure 2. The standard deviation of 45 experimental points obtained by Beattie (IO)from the smoothed data of Table I1 was 0.0062 cubic foot per pound-mole.
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This corresponded t o 0.23% deviation based upon the average molal volume. This variation is within the probable errors of the two sets of measurements. Figure 3 shows the deviation of Newitt’s measurements from the present data. I n this instance the standard deviation from the information presented in Table I1 was 0.0043 cubic foot per mole, which corresponds to 0.19yo deviation based upon the average molal volume of n-heptane ACKNOWLEDGMENT
This paper is a contribution from American Petioleum Institute Project 37 at the California Institute of Technology. Virginia Berry aided in the reduction of the data and Elizabeth McLaughlin with the preparation of the manuscript, which was reviewed by W.N. Lacey. LITERATURE CITED (1) Reattie, J. A, and Kay, W. C., J . A m . Chem. Soc., 59, 1586 (1937). (2) Bridneman. 0. C.. Ibid.. 49. 1174 (1927;. (3j Carmichael, L. T . , Sage, B: H., and Lacey, W. S . , IND.EXG. CHEM., 4 5 , 2 6 9 7 (1953). (4) Eduljee, H. E., Newitt, D. M., and %’eale, K. E., J . Chem. Soe., 1951, p. 3086. (5) Gilliland, E. R., and Parekh, M. D., IXD. ENG.CHEM.,34, 360 (1942). (6) Myers, C. H., Bur. Standards J . Research, 9 , 807 (1932). (7) Rossini, F. D., Pitzer, K. S., Arnett, R. L., Braun, R. M., and Pinientel, G. C., “Selected Values of Physical and Thermodynamic Properties of Hydrocarbons and Related Compounds,” Carnegie Press, Pittsburgh, 1953. (8) Sage, B. H., and Lacey, W. N., Trans. A m . Inst. Mining Met.
Engrs., 136, 136 (1940).
(9) Smith, E. R., and Matheson, J., J . Research A‘atl. Bur. Standards. 20.641 (1938). (IO) Smith, L. B., Beattie‘, J . A . , and Kay, W. C., J . Am. Chem. Soc., 5 9 , 1 5 8 7 (1937). (11) Stewart, D. E., Sage, B. H., and Lacey, W. N., IXD. ENG.CHEM., 4 6 , 2 5 2 9 (1954). (12) Streiff, A. J., Murphy, E. T., Sedlak, V. A., Willinghani, C. B., and Rossini, F. D., J . Research Natl. Bur. Standards, 37, 331 (1946). (13) Stuart, E. B., Yu, K. T., and Coull, J., Chem. Eng. Progr., 46, 311 (1950). RECEIVED for review January 27, 1956.
ACCEPTED March 9, 1955.
Butadiene-Aery lic Acid Copolymers C. S. MARVEL, RICHARD POTTS, JAMES ECONOiMY, AND G. P. SCOTT Noyes Chemical Laboratory, University of Illinois, Urbana, I l l .
W. I
