Inorganic Reactions in Water

Frontmatter

0. Introduction

Abstract

In general we wish to maximize the number and variety of reactions selected, trimming reluctantly from both the newer and the older literature. To permit many comparisons, we thus often omit the equations and details required to maximize success for the reactions as preparations, as in Inorganic Syntheses and the wellknown textbooks of inorganic preparations, although a few elaborations are presented for one reason or another. We hope that other variations of style prove that “variety is the spice of life”.

1. Hydrogen and the Alkali Metals

Abstract

Oxidation numbers: (-I), (0) and (I) as in SbH₃, H₂ and AsH₃, and H₂O; see Sect. 15.3 for AsH₃. The elementary substances (0) are usually omitted hereafter. We note in passing that the IUPAC name for water, oxidane, is available for future adoption.

2. Beryllium and the Alkaline-Earth Metals

Abstract

Water. Beryllium is only slightly affected by H₂O; BeO and Be(OH)₂ are insoluble in H₂O. The basic carbonate is slightly soluble, the complex fluorides, e.g., Na₂BeF₄, moderately soluble. Salts (all very toxic) such as [Be(H₂O)₄]SO₄ exemplify the tetrahedral [Be(H₂O)₄]²⁺.

3. The Rare-Earth and Actinoid Elements

Abstract

First, some notes on nomenclature. Should one use the term “lanthanide”, “lanthanon”, “lanthanoid”, or “rare earth”? The first uses the same ending, with a totally different meaning, as in “oxide” and so on. The second likewise shares its ending with the noble gasses. The third, albeit less-common, term is therefore preferred here, and by the IUPAC. All three focus attention nominally on the first member, hardly unique chemically, of the series. True, “lanthanoid” suggests “like lanthanum”, thus conceivably excluding La itself, but La is also perfectly “like” La, and may therefore be included. The resemblances make this much more convenient and economical in expression than frequently saying “lanthanum and the lanthanoids”.

4. Titanium through Rutherfordium

Abstract

Water. Titanium(III) salts are in general readily soluble in H₂O, forming a winered to violet solution, depending on the acidity. Water, above pH 7, and Ti₂O₃ ⋅ aq form TiO₂ ⋅ aq and H₂, catalyzed by 3d^II, Pt and Li+ and Na+. Titanium dioxide is insoluble in H₂O. The hydrated oxide, TiO₂ ⋅ aq, is slightly amphoteric, with both basic and acidic salts hydrolyzing readily to TiO₂ ⋅ aq. Boiling makes it less hydrated and less soluble.

5. Vanadium through Dubnium

Abstract

The relative stabilities of the Group 5 species, plus the pseudoanalog Pa, in acidic solutions, at least without strong ligands, appear to be: V^II > Nb^II ≥ Db^II > Ta^II > Pa^II;

V^III > Nb^III > Ta^III > Db^III > Pa^III;

V^IV >> Pa^IV > Nb^IV > Ta^IV > Db^IV;

Pa^V > Db^V > Ta^V > Nb^V > V^V.

6. Chromium through Seaborgium

Abstract

Oxidation numbers: mainly (II), (III) and (VI), as in Cr²⁺, Cr₂O₃ and CrO₄ ^2–, plus (IV) and (V) in peroxo complexes etc.

7. Manganese through Bohrium

Abstract

Oxidation numbers: (II), (III), (IV), (V), (VI) and (VII), as in Mn²⁺, Mn₂O₃, MnO₂, MnO₄ ^3– (“hypomanganate”), MnO₄ ^2– (manganate) and MnO₄ ^– (permanganate). Remarkably, all six oxidation states can be found, rarely or often, in a tetrahedral oxoanion, MnO₄ ⁿ⁻.

8. Iron through Hassium

Abstract

Oxidation numbers in simple species: (−II), (0), (II), (III) and (VI), as in [Fe(CO)₄]^2–, [Fe(CO)₅], Fe²⁺ (“ferrous” ion), Fe2O3 ⋅ aq (“ferric” oxide), Fe3O4 , i.e., Fe^IIFe^III ₂O₄, and FeO₄ ^2– (“ferrate”).

9. Cobalt through Meitnerium

Abstract

Oxidation numbers: (−I) in [Co(CO)₄]– (II) in Co²⁺, (III) in Co³⁺ and (IV) in CoO₂. In [Co(CO)₃(NO)] (from a non-aqueous source) we could, without further structural information, classify Co as Co⁰ but might also well see it as [Co–(CO)₃(NO⁺)] in spite of the electronegativities (because NO⁺ is isoelectronic with the very stable N₂ and CO), or as [Co+(NO^–)(CO)₃], assigning the metal as usual a positive oxidation state. (These assignments, within molecules, are partly but not entirely arbitrary.) Various experiments and calculations, not described here, also reveal NO both as a primarily neutral radical, e.g., in [Ir³⁺(Cl^–)₅(NO⁺)] and as NO⁺ in [Ru³⁺(Cl^–)₅(NO⁺)]. See 6.1.2 and 8.1.2 Oxidized nitrogen also.

10. Nickel through Darmstadtium

Abstract

Oxidation numbers: (I), (II), (III) and (IV), as in [Ni₂(CN)₆]^4–, Ni²⁺, and hydrated Ni₂O₃ and NiO₂.

11. Copper through Roentgenium

Abstract

Oxidation numbers in classical compounds: (I), (II) and (III), as in Cu₂O, “cuprous” oxide, CuO, “cupric” oxide, and Na₉[Cu^III(TeO₆)₂] ⋅ 16H₂O.

12. Zinc through Mercury

Abstract

Water. At least with dilute anions Zn²⁺ is [Zn(H₂O)₆]²⁺, although the ligancy falls from six to four with much HClO₄; cf. Br− below in 12.1.3. Zinc nitrate (6 H₂O), halides (fluoride excepted), and chlorate are deliquescent; the sulfate (7 H₂O) is efflorescent. Zinc basic carbonate, cyanide, oxalate, phosphate, arsenate, sulfide, periodate, hexacyanoferrate(II and III), and hexacyanocobaltate(III) are insoluble in water; the sulfite is sparingly soluble. Pure water (free of air) does not oxidize zinc. Zinc(2+) is hydrolyzed to Zn₂(μ-OH)³⁺, Zn₄(OH)₄ ⁴⁺ etc.

13. Boron through Thallium, the Triels

Abstract

Oxidation number in classical compounds: (III), as in both [BH₄]^– (due to the low electronegativity of B) and [B(OH)₄]^–. Non-classical [closo-CB₁₁H₁₂]⁻ etc., from non-aqueous sources, are some of the most inert and weakly coordinating anions available.

14. Carbon through Lead, the Tetrels

Abstract

Oxidation numbers in the simplest compounds: (−IV), (−II), (0), (II), (IV), as in CH₄, CH₃OH, CH₂O, CO and CO₂. Most of these, however, are well described with the older concept of valence, usually four. Still, oxidation number provides one needed criterion for sequencing here.

15. Nitrogen through Bismuth, the Pentels

Abstract

Oxidation numbers: (−III), (−II), (−I), (I), (II), (III), (IV), (V) and other, as in NH₃, N₂H₄, NH₂OH, H₂N₂O₂, NO, HNO₂, NO₂, NO₃ ^– and N₃ ^–.

16. Oxygen through Polonium, the Chalcogens

Abstract

Oxidation numbers: (−II), (−I) and (II), as in H₂O, H₂O2 and OF₂, plus fractional

values in, say, KO₂.

17. Fluorine through Astatine, the Halogens

Abstract

Water. Hydrogen fluoride, HF, a colorless, intensely corrosive gas, even for glass, is readily soluble in water to form a weak acid (distinction from the other hydrogen halides), ionized in 1-dM solution to about 10 %. A constant boiling mixture at 112 °C is about 22 M, but the more common concentrated aqueous solution (~ 49 % HF) is about 29 M. Both the solution and its vapor act on the flesh with very little warning to produce burns that are painful and slow to heal. Unlike the other hydrogen halides, HF is not a reducing acid.

18. Helium through Radon, the Aerogens

Abstract

These elements are also known as the noble or inert gasses, although not all are inert, and “aerogens” is proposed as the Group name.

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