Donald M. Richardson

Thermochemical Decomposition of Water Based on Reactions of Chromium and Barium Compounds

A potentially useful thermochemical cycle developed for the production of hydrogen and oxygen from water consists of three chemical reactions that take place in the temperature range from 400� to 1200� K. The oxidation and reduction of chromium compounds by barium hydroxide and the hydrolytic disproportionation of barium chromate(IV) and barium chromate(V), the reactions which constitute the proposed cycle, have been demonstrated.

A mixed-valency lead oxyiodide

A new, mixed-valency lead oxyiodide of variable composition, Pb(II)4−x Pb(IV)xO4O2x, has been synthesized by different routes and identified by X-ray diffraction. The reaction of massicot (yellow, orthohombic PbO) with I2 and water at room temperature produced a brown powder which consisted of crystals of almost colloidal dimensions with the above stoichiometry where 1<x<2. The crystals appear to have body-centered tetragonal symmetry with a0 = 4.10 and c0 = 13.6 A. The reaction of PbI2 and Pb3O4 at 500°C produced better crystallized specimens most likely with similar stoichiometry, Pb4O4I2 but always mixed with a considerable amount of at least one other phase, e.g. Pb(II)5O4I2( = “4PbO·PbI2”). The reaction of PbO2 with PbI2 in the temperature range of 430–550°C produced crystallized specimens with higher iodine content, e.g. Pb(II)2.5Pb(IV)1.5O4I3 (or 32 < × <2 in the above general formula), while an oxyiodide with the ideal composition, Pb(II)2Pb(IV)2O4I4 = 4PbOI (corresponding to BiOI) was never obtained. Some general reactions of the above compounds are described.

Two new copper(II) hydroxoiodides

Abstract As evidenced by X-ray diffraction, two new hydroxoiodides of copper have been synthesized and their compositions were deduced from analytical data of their mixtures. One of the compounds, with Cu/I = 4 represented by the formula Cu 4 (OH) 7 I(2.5H 2 O), had a fcc structure with a = 9.43 A and the other with Cu/I = 2.5, represented by Cu(OH) 1.4 (O) 0.2 (I) 0.1 (I 3 0.1 (0.74H 2 O) appeared to have a hexagonal (or pseudo-hexagonal) structure with a = 3.78 and c = 6.61 A . The newly found Cu(II) hydroxoiodides constitute, together with Cu 2 (OH) 3 I, the only known instances in which the ions Cu(II) and I − are present in compounds.