Thermochemical Study of the Reduction and Oxidation of Molybdovanadophosphoric Heteropoly Acids in Aqueous Solutions Full article
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Russian Journal of Inorganic Chemistry
ISSN: 0036-0236 , E-ISSN: 1531-8613 |
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Output data | Year: 1999, Volume: 44, Number: 4, Pages: 506-510 Pages count : 5 | ||
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Abstract:
The differential enthalpy (-Delta(r)H(4j)) of the reduction of 0.2 M aqueous solutions of heteropoly acids H(3+x)PV(x)Mo(12-x)O(40) (HPA-x, 1 <= x <= 3) by hydrazine hydrate (HH) at 343 K was investigated as a function of x and of the degree of reduction m = [V(IV)]/[HPA-x]. For all of the HPA-x solutions studied, the initial -Delta(r)H(4j) value (at m similar to 0) approximated 436 +/- 14 kJ per mole of HH. For an HPA-3 solution at m approximate to 0.65, a maximum in -Delta(r)H(4) was observed (approximate to 483 kJ per mole of HH) due to the interaction of the VO(2)(+) and VO(2)(+) cations in the inner coordination sphere of the HPA-3 ion. This maximum is similar to that observed in the reduction of an 0.1 M solution of VO(2)ClO(4) in 4 M HClO(4). In the case of reduction of HPA-1, HPA-2, or salts of HPA-3, no -Delta(r)H(4j) maxima were observed, because the content of VO(2)(+) in the ICS of the corresponding heteropoly anion is too low. The -Delta(r)H(4j) values for solutions of HPA-3 salts depend only on the pH but not on the nature of the cation. The enthalpies of oxidation of solutions of the reduced forms of the HPA-x by dioxygen (-Delta(r)H(2j)) were calculated. The sequence of oxidation of various V(IV) species in solutions of the reduced HPA-x is opposite to the sequence of reduction of various forms of V(V) in the initial solutions of HPA-x.
Cite:
Zhizhina E.G.
, Pankratʹev Y.D.
, Odyakov V.F.
, Matveev K.I.
Thermochemical Study of the Reduction and Oxidation of Molybdovanadophosphoric Heteropoly Acids in Aqueous Solutions
Russian Journal of Inorganic Chemistry. 1999. V.44. N4. P.506-510. WOS Scopus РИНЦ
Thermochemical Study of the Reduction and Oxidation of Molybdovanadophosphoric Heteropoly Acids in Aqueous Solutions
Russian Journal of Inorganic Chemistry. 1999. V.44. N4. P.506-510. WOS Scopus РИНЦ
Original:
Жижина Е.Г.
, Панкратьев Ю.Д.
, Одяков В.Ф.
, Матвеев К.И.
Термохимическое исследование восстановления и окисления молибдованадофосфорных гетерополикислот в водных растворах
Журнал неорганической химии. 1999. Т.44. №4. С.561-565. Scopus РИНЦ
Термохимическое исследование восстановления и окисления молибдованадофосфорных гетерополикислот в водных растворах
Журнал неорганической химии. 1999. Т.44. №4. С.561-565. Scopus РИНЦ
Dates:
Submitted: | Nov 4, 1997 |
Published print: | Apr 1, 1999 |
Identifiers:
Web of science | WOS:000207059500011 |
Scopus | 2-s2.0-0043232716 |
Elibrary | 13326669 |