2140
LEVANOV et al.
trioxide decomposition using the results of [35–37]: hydrogen trioxide is not mentioned in these works. As
Δ H = −36.5 ± 4 kcal/mol. It follows that Δ H(H O , we showed in [25], however, the thermal effects of the
1
f
2
3
aq.) = −32.4 ± 4.3 kcal/mol [25]. These values corre- final stage of the decomposition of peroxide-radical
spond to the temperature range of 220–250 K.
condensates from water vapor found by the authors of
35–37] correspond exactly to the reaction of H O
[
In [4, 17, 18, 20, 43–47], the enthalpy of formation
of hydrogen trioxide was estimated using quantum
chemical calculations for the gas phase at 298 K; the
2
3
decomposition. In addition, there are theoretical esti-
mates based on quantum chemical calculations. All
three estimates are in good agreement with one
another, and our value falls within the theoretical
interval. It would seem to be the most reliable estimate
to date.
theoretical values of Δ H °
(H O , gas) were
f
298theor
2 3
−
22.05 ± 0.95 kcal/mol. At the same time, experi-
mental values of the enthalpy of formation of H O
2
3
were determined for an aqueous solution. We can
show that the enthalpy of formation in an aqueous
solution at a temperature of Т Δ H (H O , aq.) and in
f
T
2
3
ACKNOWLEDGMENTS
This work was supported by the Russian Founda-
tion for Basic Research, project no. 13-03-00319-a.
the gas phase at 298 K Δ H ° (H O , gas) are related
f
298
2
3
by the equation
Δ H (H O ,aq.) = Δ H ° (H O , gas)
f
T
2
3
f
298
2
3
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T
2
3
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2
3
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7
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2
3
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−
(
1
1
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3
f
298
2
3
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2180 (1963).
hydr
2
3
of hydrogen trioxide in a low-temperature liquid solu-
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1
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1
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CONCLUSIONS
1
6. S. Kovačič, J. Koller, J. Cerkovnik, T. Tuttle, and
Based on the experimental heating curves of perox-
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2
2
499 (2009).
important thermodynamic properties of hydrogen tri-
oxide: the enthalpy of formation in an aqueous solu-
tion. In the literature, there are virtually no works
1
8. D. J. Grant, D. A. Dixon, J. S. Francisco, D. Feller,
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J. Phys. Chem. A 114, 8003 (2010).
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 90
No. 11
2016