Benzene empirical formula

In the mid-nineteenth century, the empirical formula of benzene, was known but its structural formula was tiot. Two proposed structures... 

Lauryl alcohol is obtained from the coconut and is an ingredient in many hair shampoos. Its empirical formula is C H. A solution of 5.00 g of lauryl alcohol in 100.0 g of benzene boils at 80.78°C Using Table 10.2, find the molecular formula of lauryl alcohol... 

Suppose that 10.0 g of an organic compound used as a component of mothballs is dissolved in 80.0 g of benzene. The freezing point of the solution is 1.20°C. (a) What is an approximate molar mass of the organic compound (b) An elemental analysis of that substance indicated that the empirical formula is C3H2C1. What is its molecular formula (c) Using the atomic molar masses from the periodic table, calculate a more accurate molar mass of the compound. 

An elemental analysis of epinephrine resulted in the following composition 59.0% carbon, 26.2% oxygen, 7.15% hydrogen, and 7.65% nitrogen by mass. When 0.64 g of epinephrine was dissolved in 36.0 g of benzene, the freezing point decreased by 0.50°C. (a) Determine the empirical formula of epinephrine, (b) What is the molar mass of epinephrine ... 

Photoexcitation of an acetylene molecule results in either dimerization or dissociation of the molecule (C2 + H2 or C2H + H). In the mass spectrometer, the major positive ions are C2H2+ (75%) and C2H+ (15%). However, at STP no gaseous products are seen under radiolysis. There are only two major products, benzene and a polymer, cuprene with an empirical formula QJH. The detailed mechanisms are still debatable. However, the following remarks may be made ... 

The simplest formula for an organic compound is called its empirical formula. This shows the elements present in the compound and the simplest ratio of the atoms of these elements in the compound. For example, ethane (C H ) has an empirical formula of CHj, whereas benzene (C H ) has an empirical formula of CH. Empirical formulae can be determined by a technique known as elemental microanalysis and you will find out more about this on p. 72. 

For instance, ortho, meta and para-mononi- trotoluenes all have the same empirical formula, C7H7N02, but the N02 group is attached to different carbons of the benzene ring... 

The solid-state hexamers (2)—(4) at first appeared to dissolve intact in benzene (94). Cryoscopic rmm measurements over a range of concentrations (0.03-0.09 M, molarity expressed relative to the empirical formula mass) implied n values of 5.9-6.1. Furthermore, their room-temperature 7Li NMR spectra in c/8-toluene each consisted of broad singlets within the narrow chemical shift (6) range of + 0.6 to -0.2 ppm (relative to external phenyllithium in the same solvent). However, variations in temperature and concentration affected the 7Li NMR spectra of (2) and, in particular, of (4) (95). Figure 18a shows these spectra for three d8-toluene solutions of (4) at -100°C. The most concentrated solution has a dominant signal at 8 -+0.7, though five or six other signals (indicated by asterisks) are apparent. On dilution,... 

When a new chemical compound is prepared, we do not know its formula. To establish the formula, we find by experiment the weights of the various atoms in the compound, and from these weights we compute the relative number of each kind of atom in the molecule. The formula so computed is the simplest formula, not necessarily the true one. It is therefore called the empirical formula. For example, we would find the empirical formula for benzene to be CH, whereas... 

It should also be noted that Leach and Migirdician37 have produced adducts of hexatriene in mixtures of benzene with certain other molecules in glassy matrices at low temperatures. Thus, along with benzene isomers which retain the empirical formula of the monomer, there may be formed photochemically other products which result from a rupture of the ring. Just possibly some of the cuprenelike polymer formed at very short wavelengths20 may be made in this way. We will return to this point in later sections. 

Exercise 22-7 Establish the structures of the following benzene derivatives on the basis of their empirical formulas and nmr spectra shown in Figure 22-6. Remember that equivalent protons normally do not split each other s resonances, a. C8H10 b. C8H7OCI c. C9FI10O2 d. C9hl12... 

Pyrrolines and Tetrahydropyridines Biltz91 first examined the action of concentrated hydriodic acid on succinonitrile and obtained a product which was claimed to contain four equivalents of hydrogen iodide. The analytical data, however, agree better with the empirical formula C4H4N2 3HI, and undoubtedly this material has the structure 114 in accordance with the recent work of Howard,92 Osborn,93 and Johnson.94 These investigators found that hydrogen bromide causes an immediate precipitation of 115 from a solution of succinonitrile in ether, benzene, or acetic... 

The empirical formula (the simplest whole number ratio of atoms in a compound) is experimentally the simplest formula of a compound that can be found. For water, the formula, H20, is both the empirical and the molecular formula. Some other examples are carbon dioxide gas, C02 methane gas, CH4 and hydrogen chloride gas, HC1. However, for the compound benzene, while the molecular formula is C6H6, the empirical formula is CH. Another example is the sugar found in honey, fructose the molecular formula is C6H1206 and the empirical formula is CH20. 

As part of his atomic theory, John Dalton stated that atoms combine with one another in simple whole number ratios to form compounds. For example, the molecular formula of benzene, C6H6, indicates that one molecule of benzene contains 6 carbon atoms and 6 hydrogen atoms. The empirical formula (also known as the simplest formula) of a compound shows the lowest whole number ratio of the elements in the compound. The molecular formula (also known as the actual formula) describes the number of atoms of each element that make up a molecule or formula unit. Benzene, with a molecular formula of C6H6, has an empirical formula of CH. Table 6.1 shows the molecular formulas of several compounds, along with their empirical formulas. 

It is possible for different compounds to have the same empirical formula, as you can see in Figure 6.6. For example, benzene and acetylene both have the empirical formula CH. Each, however, is a unique compound. Benzene, C6H6, is a clear liquid with a molar mass of 78 g/mol and a boiling point of 80°C. Acetylene, C2H2, has a molar mass of 26 g/mol. It is a highly flammable gas, commonly used in a welder s torch. There is, in fact, no existing compound with the molecular formula CH. The empirical formula of a compound shows the lowest whole number ratio of the atoms in the compound. It does not express the composition of a molecule. 

Chemists can use a mass spectrometer to determine the molar mass of a compound. They can use the molar mass, along with the molar mass of a known empirical formula, to determine the compound s molecular formula. For example, the empirical formula CH has a molar mass of 13 g/mol. We know, however, that acetylene, C2H2, and benzene, C6H6, both have the empirical formula CH. Suppose it is determined, through mass spectrometry,... 

Aspidocarpine (XLIV) was isolated by direct crystallization from the light petroleum extract of Aspidosperma megalocarpon (30), and was characterized as the perchlorate, hydrochloride, hydrobromide, and hydriodide. Its empirical formula is C22H30N2O3 and it contains one methoxyl group. Aspidocarpine represents an important chemical link between aspidospermine (II) and its relatives with one oxygen substituent in the benzene nucleus, on the one hand, and the related alkaloids with two oxygen substituents on the other, since it has been related directly with aspidospermine. 

Benzene is the oldest known organic compound, firstly discovered by Michael Faraday in 1825. When he examined the white precipitates in gas tubes used for illumination, he discovered a new compound. He determined the empirical formula of this compound as CH and named it bicarburet of hydrogen . 

The empirical formula, Fe(CO)5, has been confirmed in several analyses, and the fact that the molecule is single and correctly represented by the above formula, when the carbonyl is dissolved in benzene, has been proved by cryoscopic measurements. The solid carbonyl melts at —19 5° to —20° C., and the liquid boils at 102-5° C., under 760 mm. pressure. Its density at various temperatures has been determined as follows —... 

Formulas describe the composition of compounds. Empirical formulas give the mole ratio of the various elements. However, sometimes different compounds have the same ratio of moles of atoms of the same elements. For example, acetylene, C2H2, and benzene, CeHe, each have 1 1 ratios of moles of carbon atoms to moles of hydrogen atoms. That is, each has an empirical formula CH. Such compounds have the same percent compositions. However, they do not have the same number of atoms in each molecule. The molecular formula is a formula that gives all the information that the empirical formula gives (the mole ratios of the various elements) plus the information of how many atoms are in each molecule. In order to deduce molecular formulas from experimental data, the percent composition and the molar mass are usually determined. The molar mass may be determined experimentally in several ways, one of which will be described in Chap. 12. 

It is apparent that the compounds C2H2 and CeHe have different molecular masses. That of C2H2 is 26 amu that of CeHe is 78 amu. It straightforward to determine the molecular mass from the molecular formula, but how can the molecular formula be determined from the empirical formula and the molecular mass The following steps are used, with benzene having a molecular mass of 78 amu and an empirical formula of CH serving as an example. 

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