Compounds from formulas

Besides structure and substructure searches, Gmclin provides a special search strategy for coordiuation compouuds which is found in no other database the ligand search system, This superior search method gives access to coordination compounds from a completely different point of view it is possible to retrieve all coordination compounds with the same ligand environment, independently of the central atom or the empirical formula of the compound. 

From which compound of formula C5//8O2 was //NMR spectrum 2 obtained Conditions CDCI3, 25 °C, 90 MFlz. 

Predict formulas of ionic compounds from charges of ions. 

Find the simplest formula of a compound from chemical analysis. 

EXAMPLE D.3 Writing the formula of a binary compound from its name... 

FIGURE E.5 Each sample contains 1 mol of formula units of an ionic compound. From left to right are 58 g of sodium chloride (NaCl), 100 g of calcium carbonate (CaCO,), 278 g of iron(ll) sulfate heptahydrate (FeS04-7H.0), and 78 g of sodium peroxide (Na. O,). 

Many new drugs are discovered by studying the properties of compounds found in plants or other materials that have been used as medicines for centuries (Fig. F. 1). Once chemists have extracted a biologically active compound from a natural product, they identify its molecular structure so that it can be manufactured. This section focuses on the first step in identifying the molecular structure, the determination of the empirical and molecular formulas of the compound. 

Calculate the mass percentage of an element in a compound from a formula (Example El). 

J 3 Determine the molecular formula of a compound from its empirical formula and its molar mass (Example F.3). 

F.8 Determine the empirical formula of each of the following compounds from the data given, (a) Talc (used in talcum powder) has mass composition 19.2% Mg, 29.6% Si, 42.2%... 

If the sample consists of atoms of one element, the mass spectrum gives the isotopic distribution of the sample. The relative molar masses of the isotopes can be determined by comparison with atoms of carbon-12. If the sample is a compound, the formula and structure of the compound can be determined by studying the fragments. For example, the + 1 ions that CH4 could produce are CH4, CH3+, CH, CFI4, C+, and H4. Some of the particles that strike the detector are those that result when the molecule simply loses an electron (for example, to produce Cl I4+ from methane) ... 

Whereas technique (4) works for all alkali metals, lithium and sodium behave differently from potassium, rubidium, and cesium with respect to graphite on direct combination. The last three react facilely with graphite, to form compounds CgM (first stage) and Ci2 M (stage n > 1), but lithium reacts only under more extreme conditions of temperature or pressure, or both, to form compounds of formula CenLi (G3,... 

The crystal structures of four chlorinated derivatives of di-benzo-p-dioxin have been determined by x-ray diffraction from diffractometer data (MoKa radiation). The compounds, their formulae, cell dimensions, space groups, the number of molecules per unit cell, the crystallographic B.-factors, and the number of observed reflections are given. The dioxin crystal structures were performed to provide absolute standards for assignment of isomeric structures and have been of considerable practical use in combination with x-ray powder diffraction analysis. 

The elements classified as metals have a strong tendency to lose electrons and form atomic cations. Almost eveiy compound whose formula contains a metallic element from Group 1 or Group 2 is ionic. Other metals not only form ionic compounds in which they exist as cations but also commonly form compounds in which they share electrons. 

These five guidelines allow us to figure out the frameworks of many compounds from their chemical formulas. When the guidelines do not provide an unambiguous framework, however, we need additional stmctural information. For example, the chemical formula of benzene is Cg Hg. The guidelines tell us that the six H atoms are in outer positions but provide no help in deducing the rest of the connections. In fact, there are several possible frameworks for the chemical formula Cg Hg. We must be told that the six C atoms of benzene form a ring, with one H bonded to each C, before we can write the framework for this molecule. 

Originally, compounds containing coordination complexes were given common names such as Prussian blue (KFe[Fe (CN)g ]), which is deep blue, or Reinecke s salt (NH4[Cr (NH3)2 (NCS)4]), named for its first maker. Eventually, coordination compounds became too numerous for chemists to keep track of all the common names. To solve the nomenclature problem, the International Union of Pure and Applied Chemistry (lUPAC) created a systematic procedure for naming coordination compounds. The following guidelines are used to determine the name of a coordination compound from its formula, or vice versa ... 

Sodium, a metal, replaces iron, another metal. Fluorine, a nonmetal, replaces chlorine, another nonmetal. (In some high-temperature reactions, a nonmetal can displace a relatively inactive metal from its compounds.) The formulas for F2, NaCl, NaF, and Cl2 are written on the basis of the rules of chemical bonding (Chap. 5). 

These four molecules are the first four members of the alkanes, a homologous series of saturated hydrocarbons with the general formula, C H2 +2. The difference between them is in the number of C atoms in the compound the formula of each alkane differs from the next by one CH2 group. 

Calculate the empirical formulae of the following compounds from the information given ... 

In crystals of more complex formula, such as titanium dioxide, TiC>2, a Schottky defect will consist of two anion vacancies and one cation vacancy. This is because it is necessary to counterbalance the loss of one Ti4+ ion from the crystal by the absence of two O2- ions in order to maintain composition and electroneutrality. This ratio of two anion vacancies per one cation vacancy will hold in all ionic compounds of formula MX2. In crystals like A1203, two Al3+ vacancies must be balanced by three O2- vacancies. Thus, in crystals with a formula M2X3, a Schottky defect will consist of two vacancies on the cation sublattice and three vacancies on the anion sublattice. These vacancies are not considered to be clustered together but are distributed... 

CASRN 108-43-0 molecular formula CeHsClO FW 128.56 Photolytic. Irradiation of an aqueous solution containing 3-chlorophenol and titanium dioxide with UV light (X >340 nm) resulted in the formation of chlorohydroquinone then to hydroxyhydroquinone. Identification of compounds from the oxidation of hydroxyhydroquinone to carbon dioxide were not identified because of the low concentrations (D Oliveira et al, 1990). 

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