Binary compounds definition

In a similar way, electrochemistry may provide an atomic level control over the deposit, using electric potential (rather than temperature) to restrict deposition of elements. A surface electrochemical reaction limited in this manner is merely underpotential deposition (UPD see Sect. 4.3 for a detailed discussion). In ECALE, thin films of chemical compounds are formed, an atomic layer at a time, by using UPD, in a cycle thus, the formation of a binary compound involves the oxidative UPD of one element and the reductive UPD of another. The potential for the former should be negative of that used for the latter in order for the deposit to remain stable while the other component elements are being deposited. Practically, this sequential deposition is implemented by using a dual bath system or a flow cell, so as to alternately expose an electrode surface to different electrolytes. When conditions are well defined, the electrolytic layers are prone to grow two dimensionally rather than three dimensionally. ECALE requires the definition of precise experimental conditions, such as potentials, reactants, concentration, pH, charge-time, which are strictly dependent on the particular compound one wants to form, and the substrate as well. The problems with this technique are that the electrode is required to be rinsed after each UPD deposition, which may result in loss of potential control, deposit reproducibility problems, and waste of time and solution. Automated deposition systems have been developed as an attempt to overcome these problems. 

Thermodynamic definitions show that the first term of Eq. (1) is the enthalpy of mixing, AHu, while the second term is the negative of the excess entropy of mixing, ASm, multiplied by T. When all four parameters are zero, the liquid is ideal with a zero enthalpy and excess entropy of mixing. What has been called the quasiregular model, a = b = 0, has been used by Panish and Ilegems (1972) to fit the liquidus lines of a number of III—V binary compounds. The particular extension of this special case of Eq. (1) to a ternary liquid given by... 

Double Decomposition.—Many binary compounds may be regarded as salts of definite binary acids as well as compounds formed by the union of two elements. Among such compounds are the metallic halides, sulfides, selenides, tellurides, and peroxides. Many salts of these acids may be made by neutralizing a soluble base with the appropriate acid a much larger number may be made by the method of double decomposition (Exercise 15). 

It is well established that hydrogen forms more than one covalenl binary compound with carbon. Fluorine behaves similarly. Thus, fluorine forms CFi. C>F4. CjFV,. C.rFx and many higher hontologs. as well as the definitely imerstiiial compound (CF) . The other halogens form some similar compounds, although 10 more limited extent, and various polyhalogen compounds have been prepared. They exhibit the maximum covalencv of four and are therefore inert to hydrolysis and most other low temperature chemical reactions. 

A binary compound is made up or iwo elements in a definite molecular ratio. 

First of all, note that the term "oxidation" is based on a historical premise that is not relevant from a more modem perspective namely, the combining of another element with oxygen to form a simple binary compounds i.e., an "oxide" similarly, the removal of oxygen atoms from an oxide molecule leaving the "reduced" element was the concept intended for the term "reduction". Although this idea works fairly well for many of the more simple interactions of oxygen with both metal and non-metal elements, a better, more comprehensive, definition that includes similar reactions with other elements, such as fluorine and chlorine, evolved that was based on the transfer of electrons from one atom (or ion) to another. 

Metal carbonyl complexes are an interesting series of coordination compounds in which the ligands are CO molecules, and in many cases the metals are present in a zero oxidation state. In these complexes, both the metal and ligand are soft according to the Lewis acid-base definitions. Although the discussion at first will be limited to the binary compounds containing only metal and CO, many mixed complexes are known that contain both CO and other ligands. 

As Chapter 1 emphasizes, the law of definite proportions was one of the principal pieces of evidence that led to the acceptance of Dalton s atomic theory. It is now recognized that a great many solid-state binary compounds do not have fixed and unvarying compositions but exist over a range of compositions in a single phase. Thus, FeO (wiistite) has the composition range Feo.ssOi.oo to Feo.ssOi.oo and is never found with its nominal 1 1 composition. The compounds NiO and CuiS also deviate considerably from their nominal stoichiometries. 

Definition of a salt. A salt is a chemical compound consisting of a combination of cations and anions. However, if the cation HjO is present the compound is normally described as an acid. Compounds may have both salt and acid character. When only one kind of cation and one kind of anion are present, the compound is named as a binary compound. When the compound contains more than one kind of cation and/or anion, it is still considered to be a salt, and can be named following the guidelines below. 

Other Binary Compounds. Various borides, sulfides, carbides, nitrides, etc., have been obtained by direct interaction of the elements at elevated temperatures. Like other actinide and lanthanide metals, thorium also reacts at elevated temperatures with hydrogen. Products with a range of compositions can be obtained, but two definite phases, ThH2 and Th4H15, have been characterized. 

The regular atoms on their normal sites and the point defects occupy particular sites in the crystal structure and these have been termed structural elements by Kroger, Stieltjes, and Vink (1959) (see also Kroger (1964)). As discussed in Chapter 2, the rules for writing defect reactions require that a definite ratio of sites is maintained due to the restraint of the crystal structure of the compounds. Thus if a normal site of one of the constituents in a binary compound MO is created or annihilated, a normal site of the other constituent must simultaneously be created or annihilated. 

Many other cases of combined transport coefficients are in use, e.g. the combined (additive) transport of oxygen and metal ions commonly that we shall address later (and exemphfy by the high temperature oxidation of metals), the combination of two diffusivities involved in interdiffusion (mixing) processes, and the mass transport in creep being rate hmited by the smallest out of cation and anion diffusivities in a binary compound. As some of these sometimes are referred to as ambipolar or chemical diffusivities, we want to stress the above simple definition of ambipolar transport coefficients as relevant for membrane applications using mixed conductors. 

Liposomes are composed of a double layer in which one layer is made up of phospholipid and the internal layer is water-soluble drug (Figure 7.2). The liposome layer may be composed of naturally-derived phospholipids with mixed supermolecule chains and a variation of head group or of xmtainted artificial lipids with definite acyl chains and head groups. The phospholipids align themselves side-by-side with their oleophilic heads familiarizing themselves with one another. Medication with a wide variety of hpophilicities may be encapsulated within the liposomes, either within the phospho-hpids bilayer, within the entrapped binary compound volume or at bilayer interface. 

To quantify the value of the electrostatic potential acting on the atoms of a rigidly cut three-dimensional lattice, one has to extend the definition of the Madelung constant. In an ionic representation of a binary compound, the electrostatic potential which is exerted on an ion of type i, located in the nth plane - indexed from the vacuum side - may be written in the following way ... 

Based on the above information, the CAMD problem definition is revised as follows - The solvent can be acyclic hydrocarbons and ketones (aromatic compounds, chlorides, dioxanes are not considered for EH S concerns). The normal boiling point should be higher than that of chloroform (334 K), the molecular weight could be between 70-120, the solvent must not form azeotrope with either acetone or chloroform, and, must be totally miscible with the binary mixture of acetone and chloroform. 

There are several potential sources of error. Both methods of analysis use a binary model mixture, composed of sulfidic and thiophenic components. Thickness effects in the XANES of these model systems would alter the calibrations. There may be contributions from species not adequately represented by a simple dibenzothiophene-dibenzylsulfide model. While the XPS data are represented by 163.3 eV and 164.1 eV components, the model compound data base is as yet limited and not sufficient for a definitive interpretation in terms of alkyl sulfide and thiophenic forms. Examination by both XPS and XANES of a wider variety of model compounds and multiple component model compound mixtures will better define the sulfur species represented by these quantification methods. 

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