Hypodiphosphoric acid is the lower oxoacid of phosphorus of H4P2O6 composition. It contains the direct P—P bond, in contrast to its closest analog - pyrophosphoric acid, H4P2O7. In comparison to other phosphates the knowledge on hypodiphosphoric acid and its inorganic salts is quite limited. Since its discovery almost 150 years ago, establishment of the proper molecular and structural formula of the acid has initiated intensive research and dispute in the literature, which was decisively ended in 1964, when the first complete X-ray crystal structure determination of diammonium hypodiphosphate was reported. Since then structural studies have led to the discovery of ferroelectric properties in the above-mentioned diammonium salt and dehydration-induced staggerer-eclipsed transformation of hypodiphosphate in tetrabutylammonium salt, experimental electron density distribution determination in cubic tetralithium hexahydrate and last but not least crystal structure elucidation of hypodiphosphate analogs of adenosine diphosphate. In this mini-review the information on synthesis techniques, chemical and physical properties, applications of hypodiphosphates along with crystallochemical description of reported up-to-date crystal structures are presented.
Chleb jest jednym z podstawowych i historycznie najstarszych składników diety ludzi. Jego historia sięga 10 000 lat p.n.e. i początków rolniczej aktywności związanej z uprawą zbóż, których ziarna okazały się odżywcze.
Przedstawiono metodę wyznaczania szerokości strefy metastabilnej opartą o chłodzenie naturalne roztworu. Wykorzystując tę metodę wykonano pomiary przesycenia maksymalnego ∆cmax dla roztworów wodnych trzech soli nieorganicznych: AlK(SO4)2*12H2O, K2SO4 oraz KNO3 dla różnych warunków pracy mieszadła turbinowego. Otrzymane dane porównano z wynikami obliczeń ∆cmax metodami Synowca i Mersmanna.
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A measurement method for determination of the metastable zone width based on a natural cooling was presented. The method was used for determination of the maximum supersaturation ∆cmax for aqueous solutions of three inorganic salts: AlK(SO4)2*12H2O, K2SO4 and KNO3 at different turbine agitator’s regimes. A comparison between the experimental results and data obtained by Synowiec’s and Mersmann’s calculation methods was performed.
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The estimation of physical changes in malachite, calcite and their physical mixture caused by dry grinding were studied. Universal in this case thermogravimetry and X-ray powder diffraction as a supplementary method allowd to determinate the composition of solid products after mechanical treatment. The degree of malachite decomposition of solid products after mechanical treatment. The degree of malachite decomposition into CuO ground with calcite is appreciable higher that of malachite ground alone. The calcite, which remains undecomposed, appears to play the part of an abrasive. Partial polymorphic transformation to aragonite takes place. In all materials, the degree of crystallinity decreases.
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The use of thermogravimetry to assess the effect of mechanical activation by dry grinding of malachite was presented. The mass loss of water and carbon dioxide separately and/or together for Cu2OH2CO3 samples untreated and ground for different time was quantified. On that basis the amount of malachite decomposing during heating in thermobalance was calculated. From the measured total amount of CuO, the original mass of malachite present before mechanical treatment could be determinated. For the identification of solids, X-ray diffraction and IR spectroscopy were helpful, but only thermoanalytical techniques are universal in this case
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