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Sodium sulfite (sodium sulphite) is the inorganic compound with the chemical formula Na 2 SO 3.A white, water-soluble solid, it is used commercially as an antioxidant and preservative.
In condensed matter physics and inorganic chemistry, the cation-anion radius ratio can be used to predict the crystal structure of an ionic compound based on the relative size of its atoms. It is defined as the ratio of the ionic radius of the positively charged cation to the ionic radius of the negatively charged anion in a cation-anion compound.
Pentasil-zeolites are defined by their structure type, and more specifically by their X-ray diffraction patterns. ZSM -5 is the trade name of a pentasil-zeolite. As early as 1967, Argauer and Landolt worked out parameters for the synthesis of pentasilzeolites, particularly those relating to the following molar ratios: OH − /SiO 2 = 0.07–10, SiO 2 /Al 2 O 3 = 5–100, H 2 O/SiO 2 = 1–240. [1]
Most of molecular sieves are aluminosilicates with Si/Al molar ratio less than 2, but there are also examples of activated charcoal and silica gel. [ 2 ] [ 3 ] [ 4 ] The pore diameter of a molecular sieve is measured in ångströms (Å) or nanometres (nm).
Ionic radius, r ion, is the radius of a monatomic ion in an ionic crystal structure. Although neither atoms nor ions have sharp boundaries, they are treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.
An octahedron may then form with a radius ratio greater than or equal to 0.414, but as the ratio rises above 0.732, a cubic geometry becomes more stable. This explains why Na + in NaCl with a radius ratio of 0.55 has octahedral coordination, whereas Cs + in CsCl with a radius ratio of 0.93 has cubic coordination.
Sodium sulfide is a chemical compound with the formula Na 2 S, or more commonly its hydrate Na 2 S·9H 2 O.Both the anhydrous and the hydrated salts in pure crystalline form are colorless solids, although technical grades of sodium sulfide are generally yellow to brick red owing to the presence of polysulfides and commonly supplied as a crystalline mass, in flake form, or as a fused solid.
In atmospheric chemistry, mixing ratio usually refers to the mole ratio r i, which is defined as the amount of a constituent n i divided by the total amount of all other constituents in a mixture: r i = n i n t o t − n i {\displaystyle r_{i}={\frac {n_{i}}{n_{\mathrm {tot} }-n_{i}}}}