Journal of Chemical and Engineering Data, Vol. 23, No. 2, 1978 175
evaluated at 0 K for each reaction. This was accomplished by using eq 1 where AHfo' represents the heat of formation of
involving ground-state S atoms.
Literature Cited reactants, R, and products, P, and up and vR are the stoichiometric coefficients of the products and reactants, respectively. An equivalent method is to sum the bond dissociation energies, Doo,of the bonds that are broken and subtract from this total the bond energies of the bonds formed in the reaction. Unfortunately, few values for the heats of formation and bond dissociation energies of sulfur- and halogenGontainingmolecules have been reported in standard reference tables ( 7, 5, 70, 7 7 , 73). These data (Table I) were therefore derived by making use of eq 2 and information found in the literature. As an
D:(X-Y)
= AHf;(X)
+ AHf,"(Y)
- AHf,"(XY)
example of the use of Table I the exothermicities of four chemical reactions involving sulfur- and chlorine-containing species are listed below: S(g) t Cl(g)
+ M(g) -,SCl(g) t M(g)
AH," = -76 kcal/mol
(3)
M in reaction 3 refers to the third body involved in this termolecular reaction. S(g) t ClO(g)
SCl(g) t O,(g)
+ O(g) AH," = - 12 kcal/mol OSCl(g) + O,(g) AH,"=-75 kcal/mol
-,SCl(g) +
OSCl(g) t O,(g) +.O,SCl(g) t O,(g)
AH," = -80 kcal/mol
(4)
(5) (6)
It is also interesting to note that abstraction of a CI atom from CFCI, or CF,CI, by an S atom is slightly exothermic since the C-CI bond energies in these molecules are approximately 70-75 kcal/mol (77). S(g)
+ CF,Cl.,-,(g)
--t
S C W t CF,Cl,-,(g)
(1) Chase, M. W., Cwnvtt, J. L.,Hu, A. T., Prophet, H., Syverud, A. N., Walker, L. C. "JANAF Thermochemical Tables", 1974 Supplement, J. phys. Chem. Ref. Data, 3, 311 (1974). (2) Ciaydon, A. P., Mortimer, C. L., J. Chem. Soc., 3212 (1962). (3) Colwell, MSc. Thesis, Leeds, 1963, reported in Mackie, H., O'Hare, P. A. G., Trans. Faraday Soc., 60, 666 (1964). (4) Crutzen, P. J., Geophys. Res. Left., 3, 73 (1976). (5) Darwent, B. deB., Natl. Stand. Ref. Data Ser., Natl. Bur. Stand., No. 31 (1970). (6) Finch, A., Gardner, P. J., Radcliffe, K., J. Chem. Eng. Data, 13, 176 (1968). (7) Finlayson, B. J., Pitts, J. N., Jr., Science, 192, 111 (1976). (8) Gopinath, C. R., Rao, K. S., Curr. Scl., 42, 164 (1973). (9) Graedl, T. E., Geophys. Res. Left., 3, 181 (1976). (IO) Gurvich, L. V., Karachevtsev, G. V., Kondratiev, V. N., Lebedev, Y. A,, Medvedev, V. A., Potapov, N. K., K M e e v , Y. C., "Energies of Dissociation of Chemical Bonds, Ionization Potentials and Electron Affinities", Nauka, Moscow, 1974. (11) Hampson, R. F., Jr., Garvin, D., Natl. Bur. Stand., Tech. Note, No. 666 (1975). (12) Heicklen, J., "Atmospheric Chemistry", Academic Press, New York, N.Y., 1976. (13) Kerr, J. A., Trotman-Dickenson, A. F., in "Handbook of Chemistry and physics", 57th ed,R. C. Weast, Ed., Chemical Rubber Co. Press, Cleveland. Ohio, 1976-1977. (14) Mackle, H., Tetrahedron, 19, 1159 (1963). (15) Mackle. H., McCiean, R . T. B., Trans. Faraday Soc., 60, 669 (1964). (16) Perona, M. J., Setser, D. W., Johnson, R. L., J. Chem. Phys., 52, 6384 (1970). (17) Rowland, F. S., Molina, M. J., Geophys. Space Phys., 13, 1 (1975). (18) Stoiarski, R. S., Rundel, R . D., Geophys. Res. Left., 2, 443 (1975). (19) Stull, D. R., Prophet, H., "JANAF Thermochemical Tables", 2nd ed, Natl. Stand. Ref. Data Ser., NaN. Bur. Stand., No. 37 (1971). (20) Szabo, 2. G., "Advances in Kinetics of Homogeneous Chemical Reactions", Methuen, London, 1964, p 150. (21) Wagman, D. D., Evans, W. H., Parker, V. B., Halow, I., Bailey, S. M . , Schumm, R. H., Natl. Bur. Stand., Tech. Note, No. 270-3 (1968). (22) Wofsy, S. C., McElroy, M. B., Yung, Y. L., Geophys. Res. Left., 2, 215 (1975). (23) Wray, K., Feldman, E. V., J. Chem. Phys., 54, 3445 (1971).
(7)
The corresponding reactions of S('D,) and S('So), which are formed from photolysis of SCO in the stratosphere ( 4 ) ,are 26.4 and 63.4 kcal/mol, respectively, more exothermic than reactions
Received for review July 15, 1977. Accepted December 23, 1977. This paper is dedicated to Professor John E. Willard on the occasion of his 70th birthday. This research was supported in part by Research Corporation and the Manufacturing Chemlsts Association.
Thermodynamic Quantities for the Ionization of Water in Sodium Chloride Media to 300 "C Richard
H. Busey
and Robert E. Mesmer"
Chemistry Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
The thermodynamic quantities at the saturation pressure for the dissociation of water at rounded temperatures from 0 to 300 OC and ionic strengths to 5 m in NaCl medla are presented in tabular form. The thermodynamic parameters were derived by computer from analytical expresslons representing 0 , = [H+][OH-] presented in an earlier paper. The small dlfference in the effect of NaCl over KCI on the Ionization of water is briefly discussed. Data have been previously reported ( 7 , 3) which precisely define the ionization behavior of water, H,O(I) = H+ 4-OH-, in 0021-956817611723-0175$01 .OO/O
both NaCl and KCI media at the saturation vapor pressure of water to 300 O C . In the study of aqueous equilibria involving hydrogen ion or hydroxide ion dissociation it is often desirable to examine the thermodynamic quantities for the processes. However, the analytical expressions representing Q , [H'] [OH-] as a function of temperature, pressure, and ionic strength are sufficiently complex to require the use of computers for routine derivation of the thermodynamic parameters. These calculations have already been reported for the KCI media but not for the NaCl media (3). In this brief paper we have employed the results from ref 3 to fix the parameters describing the infinite dilution and the
0 1978 American Chemical Society
176 Journal of Chemical and Engineering Data, Vol. 23, No. 2, 1978 Table I. Thermodynamic Quantities for the Dissociation of Water at Rounded Temperatures and I o N c Strengths at the Saturation Pressure in NaCl Media hQW
s:
pvw
AH cd mole-’
c d mol?
dcg-’
cm mob-’
d mot‘fdeg-l
I = 0.0 0 25 50
75 I00 125 150 175 200 225 250 275
3w
-14.941 f 0.009 -13.993 t 0.009 -13 272 t 0.006 -I2 7 0 9 t 0 0 0 6 -12.264 t o 0 0 9 -11.914 t 0 009 -11.642rOOl2 -11.441 t 0012 -11.302 f 0.012 -11.222r 0.012 -11.196t0.015 -11.224 t 0 0 2 7 -11.301 t O . 0 4 5
14954t 63 13340t 24 I2111 t 33 11063t 57 IO045 t 84 8 9 4 3 t 89 7666 t 96 6140 t 100 4 2 9 0 t 190 2MOf 360 -710t 600 -4170t 930 -8910t 1350
-13.62 -19.28 -23.25 -26.37 -29.20
0.21 009 0 12 0.18 0:24 -32 OS 0.24 -35.15 0.24 -38 65 0 24 -42.65 0.39 -47 25 0.72 -52.59 I .20 -58.97 I .80 -67.30 2.60
:is.?-t
-4
2
-55.3t
I 5
-44.4
t
1.2
-40.4
t
1.2 1.2 1.2 30 3.6 7.2 9.3 10.8 14.1 22.2
-41.7t -47.0t -55.6t -67.1 t -81.4: -99.1 t -122.2 t -158.1 t
-230.3t
-- -. -24.1 t -23.0t -22.8 t -23.1t -25.8 f -29.2 t -34.0
f
22 1.9 1.7 1.6 1.6 1.6 1.7
40.3t 1.8 4 8 . 3 t 2.3 -59.6 f 3.3 -76.4 t 5.1 -1059: 9.2 -166.1 f 18.3
I = 0.1
0 25 50
75 100
125 150 175 200 225 250 275
3w
0 25 50
75
IO0 125 I50 I15
200 225 250 275
300
-14.738 i 0.006 -13.780 t 0 006 -13.046 f 0.006 -12467 f 0006 -12.004 t 0.006 -I1 631 f 0.009 -11.335 f 0.012 -11.104 f 0.012 - 1 0 9 3 2 t 0012 -10 811 t 0.012 -10 735 t 0.015 -10.695 t 0.024 -10.683 f 0.042
lSO8Ot 63 13520t 24 123781 32 11445t 54 10561t 84 9 6 3 0 t 99 8 5 5 2 t 100 7 2 8 5 t 100 5 8 l O t 170 4 1 2 0 t 330 2260t 560 2 1 0 t 860 -2260t1240
-14 663 f 0.009
151429 13652t 12609r 11801* 11073t 10311 f 9443r 8438t 7310t 6140t
-13 701 f 0.006 -I2 957 t 0.006 -12.365 t 0 009 -11.883 t 0.009 -11.489tOOl2 -11 1 6 7 t 0 . 0 1 5 -10 907 t 0.015 -10.701 f 0.018 -10.540r 0018 -10.416: 0 0 2 1 -10.316 t 0.030 -10 226 t 0.045
69 45 51 66 90 105
105 105 170 320 5 M O t 550 4 1 7 0 t 880 3570 f 1310
-12.23 -17.70 -21.39 -24 17 -26 61 -29 03 -31.65
0.21 0.09
0.12 0.18
0.24
0.27 0.30 0.30 -37.75 0 36 -41.19 0.66 -44.80 0 80 -48.50 I .70 -52 80 2.30 -34 5s
I = 0.5 -11.67 -16 90 -20.27 -22.68 -24.70 -26.67 -28.78 -31.08 -33.51 -35.90 -38.02 -39.60 -40.60
0.24 0.15 0.18 0.21 0.27 0.30 0 30 0 30 0.39 0.66 0 81 I10 2.60
-74.2 t 4.2 -52.4t 1.5 -40.3t 1.2 -35 4 t 1.2 -35.7t 0.9 -39.9t 1.2 -46.6 t 3.0 -54 9 t 3 3 -63.4 t 6.9 -7l.Or 9.0 -77.8 t 9.9 -88.0t 13.0 -116.0t 20.0
-72.0t -49.Ot -35.8
-29.8 -29.2 -32.3 -37.4 -42.9 -46.6 -46.4
t t t t t t
f t
-40.4
2
-29.0 -20.9
f
f
-23.20 t -22.00r -21 68 ~. ..* -22.38 t -24 2 0 t -27.19 t -31.38t -36.86 t -43.90 f -53.33 f -67.42 f -92.03i -141 70 t
4.2 1.5 1.2
-22.1t
1.2
-20.8 f -22.2 f -24.7 f -28.2 t -32.6t -38.2 t 45.6 t -56.4 t -74.9 t -111.6 t
1.2 1.2 2.7 3.0 6.6 8.7 10.5 15.9 28.8
1.8 14 14 . 1.3 1.2 1.2 1.2 1.4 1.8 2.6 4.1
70 19.0
1.5
-20.8 f 1.2 -20.3 f 1.2 1.1 1I 1.1 1.2 1.3 1.6 2.2 3.5
6.4 13.2
1’1.0 0
25 50
75 100 125 150 175 2-24 225 250 275 300
-14.684 f 0.009 -13.718 t 0.008 -12.969 i 0.009 -12.366 i 0.009 -11.872t 0.010 -11.462 f 0.010 -11.121 f 0.010 -10.839 f 0.011 -10.608 f 0.012 -10418t0.014 -10.259 t 0.016 -10.117 f 0.019 -9.976 t 0.023
15146r 67 13718t 56 127571 45 12051 t 35 11442t 33 108193 45 10113t 67 9305 t 95 &00*130 7600 t 160 6970 t 200 68101 230 7320 i 300
-14.931 t0.017 -13966t0.011 -13.203 3 0.014 -12.576r 0.017 -12,044 t 0019 -11.587 t 0.021 -11.190 i 0.021 -10.842 i0.023 -10.536 t 0.027 -10.261 f 0.033 -10.005 t 0.042 -9.753 t 0.033 -9 482 t 0.066
15040 t 13830 t 13130: 12740t
-11.74 -16.76 -19.86 -21.97 -23.66 -25.27 -26.99 -28.83 -30.72 -32.41 -33.61 -33.87 -32.87
0.23 0 19 0.16 0 13 0.11 0.13 0 17 0.23 0.30 0.37 0.45
0.53 0.62
-69.9 t -46.1 t -32 1 f -25 4 t -24.0 t -26.3 t -30.3 t
0,s 0.6 0.7
0.8 0.9
1.0 1.1 -34.1 t 1.3 -35.1 f 1.5 -30.5 t 1.6 -17.4 t 1.7 5.8t1.9 35.6 t 2.1
-21.2 f -19.8 t -19.3r -19.6 f
1.5
1.4 1.3 1.3
25 50
75 100
125 150
175 200 225 250 275
300
200 170 130 110 12500 t 100 12300 t 140 12080 i 200 I1850 1 280 11670 t 380 11710 t 490 12240 f 610 13660 t 750 16550 t 900
-13.25 0.69 -17 53 0.57 -19.79 0.45 -20.95 t 0.36 -21.62 t 0.32 -22.13 t 0.37 -22.64 t 0.50 -23 17 f 0.68 -23.54 t 0.88 -23.40 t 1.10 -22.40 t 1.30 -19.70t 1.60 -14.50 t 1.90
-62.4 -36.6 -20.6
t
1.4
f
1.7 2.0
-11.8 -8.2 -8.1
t
-9.1 -9.0
2 t
2.3 27
t
3.0
t
3.4
3.8 -4.2 t 4.3 9.1 t 4.8 35.8 t 5 2 81.7 t 5.8 155.6 t 6.3 t
50
75 100
125 150
175 200 225 250 275
300
f 0.033 -14.291 t 0.026 -13.518t 0.029 -12.869 t 0034 -12.306 t 0.037 -11.807 t0.038 -11.360 t 0 039 -10.954 t 0.042 -10.582 t 0048 -10 234 t 0.058 -9.896 f 0.072 -9.551 i 0.089 -9 I77 f 0.110
-15.254
14890t 340 13880t 280 13420t 220 133101 110 13400t I70
-15.27 -18.85 -20.33 -20.65
13580r 230 13790t 340
-19.92 -19 38 -18 75 -17 90 -16.30 -1360 -8.90 -0.90
140609 470 14460t 640 1 5 2 W t 820 16580tlO20 l 9 l l O t 1250 23600t1500
1.15 0.95 0.76 0.60
20.40 0.53 0.62 0.84
1.13 1.50 1.80
2.20 2.60 3 10
-55.3 -27.9 -10.1
f
2.4
t
2.8 33 3.9
I
0.4 f
5.9 8.1: 9.4 t 12.5t 21.0t 39.6 t 74.2r 133.2 t 233 3 t
4.4
5.1 5,7 6.4 7.1 1.9 8.7 9.6 10.5
+
where
-22.9t 1.4 -25.8 t 1.5 -29.5 f 1.5
F(r) = [ 1 - (1 + 2(Z1 ) - 21) exp(-2(Z1 / * ))] /41
1.8
-34.0
t
-39.8 48,l -62.1 -89.1
f
2.4
i
4.0
t
7.7 17.0
f
-19 I t 2.3 -17.5 t 2.3 -16.7 1 2.3 -16.6 + 2.3 -17.1 t 2.4 -18.2 t 2.6 -19.8 t 1.7 -21.6 t 2.9 -23.4 t 3.2 -25.3 t 4.2 -21.4 f 7.1 -30.0 t 14.0 -32.7 t 32.0
1=5.0
0 25
+
log Q, = (3.1286 X lo4/? 94.9734 In T0.09761 1T- (2.17087 X 106/T2)- 606.522 + 2A(Z1”)/(1 (Z1I2))- [0.61139- (87.645/T)1.6698 X 10-6TZ+ 0.24456F(Z)]I- 0.0157@~m,,,, + p(12.99535 - O.Ol4449T- 4.219071 X 10-3(Z1’2)T+ 7.05620 X 10-7(Z1’z)T2)(P -Ps) (1
-20.8 i 1.3
I = 3.0
0
pressure-dependent behavior. The needed derivatives were obtained by numerical differentiation of eq 1 below. Table I lists the values for AH, AS,AC,, and AVwhich best describe the ionization process in NaCl at the saturation pressure of water at six ionic strength values and at 25 OC intervals from 0 to 300 OC. The errors given (three times the standard error) for the quantities at ionic strengths of 0.5 or less are taken from ref 3 and at higher ionic strength values they were obtained by propagation of the errors assigned to the data in ref 1. The difference in the effect of NaCl over KCI on the ionization of water is relatively small. Below unit ionic strength log Q, values in the two media agree within less than 0.05 units, at higher ionic strengths and at the higher temperatures log Q, for NaCl are more positive than the values in KCI solution by larger amounts, reaching a maximum of 0.151 difference at 250 OC and I = 3.0. There is a small but regular trend toward reduced AHvalues for NaCl over KCI media at the higher temperatures as the ionic strength increases, e.g., 7320 f 300 vs. 10950 f 1820 cal mol-‘ for NaCl and KCI media, respectively, at 300 OC and I = 1.0, and 16 500 f 900 vs. 21 380 f 3500 cal mol-’, respectively, at 300 OC and I = 3.0. Similarly, more negative AS values at the higher salt concentrations are shown for NaCl medii, -14.50 f 1.90 vs. -6.50 f 6.60 cal mot’ deg-’ for NaCl and KCI solutions, respectively, at 300 OC and I = 3.0. The basis for the thermodynamic data are the expressions ( 7 , 3)
-17.6 -15 9 -14.9 -14.5 -14.6
+
A=-2.97627 4.80688 X 10-’T- 2.69280 X 10-4T2 + 7.49524 X 10-7T3- 1.02352 X 1 0 - 9 p + 5.58004 X 10-13~5 (3) p = [50.9929 -0.233581t+ 1.9750 X 10-3t2 1.78505 X exp(0.0380606)tl X bar-’ (4)
+
(4 = osmotic coefficient of the NaCl solution (Z),P, is the vapor pressure of water at T(K), tis in OC, and lis the ionic strength.)
Llterature Cited (1) Busey, R. H., Mesmer, R. E., J . Solution Chem., 5 , 147 (1976). (2) Liu, C., Lindsay, W. T., J . Solution Chem., 1, 45 (1972). (3) Sweeton, F. H., Mesmer, R. E., Baes, Jr., C. F.,J . Solution Chem., 3, 191 (1974).
-15.1
-15.7 -16 1 -16 I -15.3
-13.1 -7.9 6.1
Received for review August 5, 1977. Accepted November 3, 1977. Research sponsored by the Division of Physical Research of the Energy Research and Development Administration under contract with Union Carbide Corp.
