Rock salt, NaCl

X-ray structural studies have played a major role in transforming chemistry from a descriptive science at the beginning of the twentieth century to one in which the properties of novel compounds can be predicted on theoretical grounds. When W.L. Bragg solved the very first crystal structure, that of rock salt, NaCl, the results completely changed prevalent concepts of bonding forces in ionic compounds. 

Sodium, 22 700 ppm (2.27%) is the seventh most abundant element in crustal rocks and the fifth most abundant metal, after Al, Fe, Ca and Mg. Potassium (18 400 ppm) is the next most abundant element after sodium. Vast deposits of both Na and K salts occur in relatively pure form on all continents as a result of evaporation of ancient seas, and this process still continues today in the Great Salt Lake (Utah), the Dead Sea and elsewhere. Sodium occurs as rock-salt (NaCl) and as the carbonate (trona), nitrate (saltpetre), sulfate (mirabilite), borate (borax, kemite), etc. Potassium occurs principally as the simple chloride (sylvite), as the double chloride KCl.MgCl2.6H2O (camallite) and the anhydrous sulfate K2Mg2(S04)3 (langbeinite). There are also unlimited supplies of NaCl in natural brines and oceanic waters ( 30kgm ). Thus, it has been calculated that rock-salt equivalent to the NaCl in the oceans of the world would occupy... 

The compound Li4Nb04F crystallizes in cubic syngony, with a cell parameter of 4.192 A and a Rock Salt (NaCl) structure. The compound s X-ray diffraction pattern and cell parameter are very similar to those of nickel oxide, NiO. 

Thus, in cubic oxyfluorides of niobium and tantalum with rock-salt (NaCl) crystal structures, the formation and extinction of spontaneous polarization occurs due to polar ordering or disordering of Li+ - Nb5+(Ta5+) dipoles. 

Fluorine comes from the minerals fluorspar, CaF, cryolite, Na3AlF6 and the fluorapatites, Ca,F(P04)3. The free element is prepared from HF and KF by electrolysis, but the HF and KF needed for the electrolysis are prepared in the laboratory. Chlorine primarily comes from the mineral rock salt, NaCl. The pure element is obtained by electrolysis of liquid NaCl. Bromine is found in seawater and brine wells as the Br ion it ts also found as a component of saline deposits the pure element is obtained by oxidation of Br (aq) by Cl,(g). Iodine is found in seawater, seaweed, and brine wells as the I" ion the pure element is obtained by oxidation of I (aq) by Cl,(g). 

Most monochalcogenides of the Group 3 metals adopt the rock salt (NaCl) structure. Note that the crystal chemistry of divalent europium is very similar to that of the alkaline earths, particularly strontium, as the radius of Eu is almost the same as that of Sr ". For the Yb compounds, the cell dimensions are practically identical with those of the Ca compounds. 

Explain why MgO crystallizes in the rock salt (NaCl) structure whereas BeO crystallizes in the wurtzite structure. 

The sodium chloride structure, AX systems. Cubic Fm3m (Space Group 225) The sodium chloride or rock salt, NaCl, structure has a simple face-centered cubic unit cell (Figure 8) with alternating cations-anions along the three cubic axes. 

The simple cubic structme, sometimes called the rock salt structure because it is the structme of rock salt (NaCl), is not a close-packed structure (see Figure 1.20). In fact, it contains about 48% void space and as a result, it is not a very dense structure. The large space in the center of the SC structme is called an interstitial site, which is a vacant position between atoms that can be occupied by a small impurity atom or alloying element. In this case, the interstitial site is surrounded by eight atoms. All eight atoms in SC me equivalent and me located at the intersection of eight adjacent unit cells, so that there me 8 x (1/8) = 1 total atoms in the SC unit cell. Notice that... 

Apparatus A Beckman, Single Beam Infrared Spectrophotometer, Model IR 2, with rock salt (NaCl) optics was used in accordance with the instruction manual for the instrument. All ab- sorbance measurements were made at the peaks of the bands, using a single NaCl cell of about < 0.2mm thicknss previously calibrated by the interference fringe method described >n Ref 1 and found to be 0.209mm in thickness. Condition... 

For a 1 1 solid MX, a Schottky defect consists of a pair of vacant sites, a cation vacancy, and an anion vacancy. This is presented in Figure 5.1 (a) for an alkali halide type structure the number of cation vacancies and anion vacancies have to be equal to preserve electrical neutrality. A Schottky defect for an MX2 type structure will consist of the vacancy caused by the ion together with two X anion vacancies, thereby balancing the electrical charges. Schottky defects are more common in 1 1 stoichiometry and examples of crystals that contain them include rock salt (NaCl), wurtzite (ZnS), and CsCl. 

Rg. 4.18 Actual crystal structures of the alkali halides (as shown by the symbols) contrasted with the predictions cl the radius ratio rule. Tie figure is divided into three regions by the lines rjr. 0.414 and r+/h- a 0.732, predicting coordination number 4 (wurizite or zinc blende, upper left), coordination number 6 (rock salt, NaCl, middle), and coordination number 8 (CsCI, lower right). The crystal radius of lithium, and to a lesser extent that of sodium, changes with coordination number, so both ihe radii with C.N. 4 (left) and C.N = 6 Iright) have been plotted. 

In practice, infrared spectra can be obtained with gaseous, liquid, or solid samples. The sample containers (cells) and the optical parts of the instrument are made of rock salt (NaCl) or similar material that transmits infrared radiation (glass is opaque). 

Chlorine comes primarily from the mineral rock salt (NaCl). The pure element is obtained by electrolysis of liquid NaCl. 

Halide Rock salt NaCl Sodium chloride... 

The alkali metals react with many other elements directly to make binary solids. The alkali halides are often regarded as the most typical ionic solids. Their lattice energies agree closely with calculations although their structures do not all conform to the simple radius ratio rules, as all have the rock salt (NaCl) structure at normal temperature and pressure, except CsCl, CsBr and Csl, which have the eight-coordinate CsCl structure. The alkali halides are all moderately soluble in water, LiF being the least so. 

Table Some binary structures based on close-packed arrays of anions Array Holes filled Structure type Examples Fee All octahedral Rock salt (NaCl) LiF, MgO V2 octahedral Cadmium chloride MgCl2...

Materials sodium chloride, rock salt, NaCl, 117 grams = 2 F.W. 

Chemically Pure Sodium Chloride from Rock Salt, NaCl... 

Gather these materials Three small glasses filled with water 1 crystal of potassium permanganate (KMn04) 1 crystal of rock salt (NaCl) a glass rod black India ink an eye dropper. 

Sodium and K have high abundances (2.6 and 2.4%) in the lithosphere and occur in large deposits of rock salt, NaCl, and camallite, KCl-MgCl2-6H20. Lithium, Rb, and Cs have much lower abundances and occur mainly in a few silicate minerals. 

Chlorine Yellow-green gas 0.14 -101 -34 Rock salt (NaCl), halite (NaCl), sylvite (KC1) Electrolysis of aqueous NaCl... 

All of the alkaline earth oxides, MO, except one crystallize in the rock salt (NaCl) structure. What is the exception and what is the likely structure for it (Wells, A, F. Structural I Inorganic Chemistry, 5th ed. Oxford University Oxford, 1984.)... 

Sodium chloride rock salt (NaCl ) has been shown to help improve asparagus production while helping plants to resist disease. 

A rock salt (NaCl), ice, and water mixtnre is nsed to cool milk and cream to make homemade ice cream. How many grams of rock salt must be added to water to lower the freezing point 10.0°C ... 

As an example, an electron diffraction investigation of (CsI) Cs" cluster structures (n = 30-39) are presented in Fig. 1.24. From the mass-resolved diffraction pattern contributions of both, rock salt (NaCl) and bulk cesium chloride lattice (CsCl) derived isomeric structures are observed at size n = 32. This particular size can form a closed shell rhombic dodecahedron corresponding to the Csl bulk structure. Interestingly, all other investigated sizes (n 32) are dominated by the rock salt structure [147]. In Fig. 1.24a the molecular diffraction data and the best fits for (CsI) Cs" cluster sizes n = 31, 32, and 33 obtained at 300 K are displayed. The plot in Fig. 1.24b shows the diffraction... 

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