Abstract
The volumetric specific heats (in J-K−1-cm−3) of tetraalkylammonium bromides (R 4 NBr) have been measured at 25°C in the concentration range 0.02 to 0.4 aquamolal in H 2 O and D 2 O with a differential flow microcalorimeter. The apparent molal heat capacities φc, calculated from the specific heats and known densities, were fitted with the equation φc=φ oc +Acm1/2+Bcm whereA c is the Debye-Hückel limiting slope andB c is an adjustable parameter.
The standard heat capacity of transfer ΔC optr =φ oc (D 2 O-φ oc (H 2 O) of R 4 NBr is positive forR equal ton-propyl andn-butyl and negative for methyl and ethyl. Except for Me 4 NBr in H 2 O, allB c are negative and become more so as the size of the cation increases;B c is usually more negative in D 2 O. These results can be interpreted with a two-state model for water and show that a positive ΔC optr is evidence that the solute is an overall structure maker, while a negative value indicates a net structure breaker. The negativeB c is consistent with the existence of strong solute-solute structural (mostly hydrophobic-hydrophobic and hydrophobic-hydrophilic) interactions in the solution.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
R. E. Kerwin, Ph.D. thesis, University of Pittsburgh, 1964.
Y. C. Wu and H. L. Friedman,J. Phys. Chem. 70, 166 (1966).
R. L. Kay and D. F. Evans,J. Phys. Chem. 69, 4216 (1965).
C. V. Krishnan and H. L. Friedman,J. Phys. Chem. 74, 2356 (1970).
J. E. Desnoyers, R. Francescon, P. Picker, and C. Jolicoeur,Can. J. Chem. 49, 3460 (1971).
E. Whalley,Trans. Faraday Soc. 53, 1578 (1957).
C. G. Swain and R. F. W. Bader,Tetrahedron 10, 183 (1960).
G. Némethy and H. A. Scheraga,J. Chem. Phys. 41, 680 (1964).
B. E. Conway and L. H. Laliberté,Trans. Faraday Soc. 66, 3032 (1970).
H. S. Frank and W. Y. Wen,Discussions Faraday Soc. 24, 133 (1957).
G. C. Kresheck,J. Chem. Phys. 52, 5966 (1970).
P. Picker, P. A. Leduc, P. R. Philip, and J. E. Desnoyers,J. Chem. Thermodyn. 3, 631 (1971).
R. L. Kay, J. Vituccio, C. Zawoyski, and D. F. Evans,J. Phys. Chem. 70, 2336 (1966);
R. L. Kay,Advan. Chen. Ser. 73, 1 (1968).
K. W. Bunzl,J. Phys. Chem. 71, 1358 (1967).
H. Ruterjans, H. F. Schreiner, V. Sage, and T. H. Ackermann,J. Phys. Chem. 73, 986 (1969).
T. S. Sarma, R. K. Mohanty, and J. C. Ahluwalia,Trans. Faraday Soc. 65, 2333 (1969).
E. M. Arnett and J. J. Campion,J. Am. Chem. Soc. 92, 7097 (1970).
G. Perron and J. E. Desnoyers,J. Chem. Eng. Data 17, 136 (1972).
G. N. Lewis and M. Randall,Thermodynamics, 2nd ed. revised by K. S. Pitzer and L. Brewer (McGraw-Hill, New York, 1961), Chap. 23, pp. 338–339.
V. K. La mer and I. A. Cowperthwaite,J. Am. Chem. Soc. 55, 1004 (1933).
C. G. Malmberg and A. A. Maryott,J. Res. Nat. Bur. St. 56, 1 (1956); C. G. Malmberg,ibid.,60, 609 (1958).
G. S. Kell,J. Chem. Eng. Data 12, 66 (1967).
E. A. Guggenheim and J. E. Prue,Trans. Faraday Soc. 50, 710 (1954).
H. S. Harned and B. B. Owen,The Physical Chemistry of Electrolytic Solution (Reinhold, New York, 1958), 3rd ed., Chap. 5, p. 173.
G. N. Lewis and M. Randall,Thermodynamics, 2nd ed. revised by K. S. Spitzer and L. Brewer (McGraw-Hill, New York, 1961), Appendix 4, p. 640.
N. Burns, Ph.D. Thesis, University of Alberta, 1968.
W. Kauzmann,Advan. Protein Chem. 14, 1 (1959).
D. Eisenberg and W. Kauzmann,The Structure and Properties of Water (Oxford Press, New York, 1969), p. 181.
A. Ben-Naim,Trans. Faraday Soc. 66, 2749 (1970).
C. M. Criss and J. W. Cobble,J. Am. Chem. Soc. 86, 5390 (1964).
R. M. Noyes,J. Am. Chem. Soc. 86, 971 (1964).
J. E. Desnoyers and G. Perron,J. Solution Chem. 1, 199 (1972).
M. E. Friedman and H. A. Scheraga,J. Phys. Chem. 69, 3795 (1965); J. E. Desnoyers and M. Arel,Can. J. Chem. 45, 359 (1967).
B. E. Conway and R. E. Verrall,J. Phys. Chem. 70, 3952 (1966); J. E. Desnoyers and P. R. Philip,Can. J. Chem. 50, 1094 (1972).
F. J. Millero and W. Drost-Hansen,J. Phys. Chem. 72, 1758 (1968).
J. E. Desnoyers, M. Arel, G. Peron, and C. Jolicoeur,J. Phys. Chem. 73, 3346 (1969).
R. W. Gurney,Ionic processes in Solution (McGraw-Hill, New York, 1954).
P. R. Philip and J. E. Desnoyers,J. Chim. Phys. (to be published).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Philip, P.R., Desnoyers, J.E. Apparent molal heat capacities of transfer from H2O to D2O of tetraalkylammonium bromides. J Solution Chem 1, 353–367 (1972). https://doi.org/10.1007/BF00715993
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00715993