The γ radiolysis of deaerated aqueous solutions containing sodium bicarbonate and either glucose or isopropanol has been studied at ∼20° in the applied pressure range 0 to 7 kbar. For 0.05M bicarbonate and 0.036M isopropanol, G(H2) increases from 0.89 to 2.43 as applied pressure increases from 0 to 6.9 kbar. A 100‐fold change (0.005–0.5M) in bicarbonate concentration has little or no effect on the pressure dependence of G(H2). Because primary yields are invariant over the pressure range studied, the results are interpreted in terms of an effect of pressure on the competition between Reactions [2] and [3]with Reaction [3] followed by Reaction [4]Such an interpretation gives a difference in activation volumes of Reactions [2] and [3] as ΔV2‡—ΔV3‡≈18.4 ml mole−1 and a specific rate k30≈6×105M−1· sec−1 at atmospheric pressure. Assumption that Reaction [2] is diffusion controlled permits estimation of ΔV2‡≈1.6 ml mole−1, from the pressure dependence of water viscosity. Thus, ΔV3‡≈−16.8 ml mole−1. The latter value, in turn, yields an estimate of V̄(eaq−) in the range −10.9 to −6.5 ml mole−1 relative to V̄(H+)=0. Use of an absolute value of V̄0(H+)=−5.4 ml mole−1 gives an absolute value of V̄0(eaq−) in the range −5.5 to −1.1 ml mole−1. Approximate equality of the values for V̄0 of the electron and of the proton is consistent with their having a negligible intrinsic volume and approximately equal electrostriction volumes.
REFERENCES
1.
2.
R. R.
Hentz
, Farhataziz
, D. J.
Milner
, and M.
Burton
, J. Chem. Phys.
46
, 2995
(1967
).3.
4.
A. O. Allen, The Radiation Chemistry of Water and Aqueous Solutions (D. Van Nostrand Co., Inc., Princeton, N.J., 1961), p. 41.
5.
S.
Gordon
, E. J.
Hart
, M. S.
Matheson
, J.
Rabani
, and J. K.
Thomas
, Discussions Faraday Soc.
36
, 193
(1963
).6.
L.
Kevan
, P. N.
Moorthy
, and J. J.
Weiss
, J. Am. Chem. Soc.
86
, 771
(1964
).7.
The decrease in with increase in bicarbonate concentration (cf. Fig. 1) is attributed to scavenging of certain precursors of within the spurs.
8.
9.
S. D. Hamann, High Pressure Physics and Chemistry, R. S. Bradley, Ed. (Academic Press Inc., New York, 1963), Vol. 2, (a) p. 150;
(b) pp. 150, 152, 186, and 188;
(c) pp. 168–171, 182–184, and 200–203;
(d) p. 148.
10.
H. S.
Golinkin
, W. G.
Laidlaw
, and J. B.
Hyne
, Can. J. Chem.
44
, 2193
(1966
).11.
12.
L. Pauling, The Nature of the Chemical Bond (Cornell University Press, Ithaca, N.Y., 1945), p. 189.
13.
14.
15.
16.
17.
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© 1967 American Institute of Physics.
1967
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