Moles calculations

Sixty-two grams (61 ml., 0.67 mole) of aniline (Note 1) is mixed with 68.5 g. (0.66 mole) of benzonitrile in a 250-ml., widemouthed flask, and, during about 20 minutes, 89 g. (0.67 mole, calculated as AICI3) of a freshly opened sample of powdered, anhydrous aluminum chloride is added in portions with thorough stirring (Note 2). The mixture is then heated at 200° for 30 minutes (Note 3), and, while still molten, is poured slowly into a thoroughly stirred mixture of 20 ml. of concentrated hydro-... 

At best, van der Waals interactions are weak and individually contribute 0.4 to 4.0 kj/mol of stabilization energy. ITowever, the sum of many such interactions within a macromolecule or between macromolecules can be substantial. For example, model studies of heats of sublimation show that each methylene group in a crystalline hydrocarbon accounts for 8 k[, and each C—IT group in a benzene crystal contributes 7 k[ of van der Waals energy per mole. Calculations indicate that the attractive van der Waals energy between the enzyme lysozyme and a sugar substrate that it binds is about 60 k[/mol. 

The heat of solution tends at extreme dilution to the value +4207 cal/mole. Calculate the conventional free energy of solution at 25°C and the conventional entropy of solution. 

The value for K was determined to be 10 litre mole at 20°C, which is of the same order of magnitude as those for tertiary alkyl cations ((0-07 — 2) X 10 litre mole . Section II) and dramatically different from those for secondary alkyl cations (about 10 ° litre mole , calculated from Figs. 2 and 3). These data show that the 2-norbomyl ion is only 1-6 kcal mole less stabilized than, for example, the tertiary butyl cation and about 8 kcal mole" more stabilized than secondary alkyl cations. Another thermodynamic argument for the high stability of the 2-norbornyl ion in solution is found in the work of Amett and Larsen (1968)... 

Redox reactions may involve solids, solutes, gases, or charge flows. Consequently, you must be prepared for all the various conversions from molar amounts to measurable variables. As a reminder. Table 19-2 lists the four relationships used for mole calculations. 

With molarity and volume of solution, numbers of moles can be calculated. The numbers of moles may be used in stoichiometry problems just as moles calculated in any other way are used. Also, the number of moles calculated as in Chap. 8 can be used to calculate molarities or volumes of solution. 

Solid calcium carbonate decomposes to produce solid calcium oxide and carbon dioxide gas. The value of AG° for this reaction is 130.24 kJ/mole. Calculate AG at 100°C for this reaction if the pressure of the carbon dioxide gas is 1.00 atm. 

The key to any reaction experiment is moles. The numbers of moles may be calculated from various measurements. A sample may be weighed on a balance to give the mass, and the moles calculated with the formula weight. Or the mass of a substance may be determined using a volume measurement combined with the density. The volume of a solution may be measured with a pipet, or calculated from the final and initial readings from a buret. This volume, along with the molarity, can be used to calculate the moles present. The volume, temperature, and pressure of a gas can be measured and used to calculate the moles of a gas. You must be extremely careful on the AP exam to distinguish between those values that you measure and those that you calculate. 

B—The molar mass may be obtained by dividing the grams by the number of moles (calculated from the ideal gas equation). Do not forget to convert the temperature to kelvin. 

The experimental values are taken from Kortum, Vogel, and Andrussow (1961). Values in square brackets are -kgT Ing (in kcal/mole) calculated at 25 quantities in the sense discussed in Appendix J. 

Table 5.74 Main solid-solid reaction adopted in geothermobarometry. Values of 15.11% j (kJ/ mole), ASp [J/(mole X K)], A V% (cmVmole), and A G% t, (kJ/mole) calculated with INSP and THERMO computer packages (Saxena, 1989).

If the activation energy of a reaction is 80.9 kJ mole-, calculated the fraction of molecules at 400° C, which have enough energy to react to form products ... 

Singlet-triplet splitting in kilocalories per mole calculated at the BLYP/6-311G(d,p) level of theory. BLYP/6-311G(d,p) bond lengths r in picometers, vibrational frequencies in reciprocal centemeters. Observed position of the characteristic C—C/C—F stretching vibration in reciprocal centemeters. 

Divide the given mass of solute by the number of moles calculated in Step 4. This is your molecular mass, or number of grams per mole, from which you can often guess the identity of the mystery compound. 

The infrared absorption spectrum thus showB that o-chlorophenol in solution in carbon tetrachloride consists of about 91 percent cis molecules and 9 percent trans molecules. The cis molecules are more stable than the trans molecules by a standard free-energy difference of about 1.4 kcal/mole (calculated from the ratio of the areas of the peaks). This is presumably the difference in free energy of the cis molecule with its intramolecular hydrogen bond and the trans molecule with a weaker hydrogen bond with a solvent molecule. 

The combustion of CjHsOH, in a bomb calorimeter at constant volume gives a value of A ° = -326.1 kcal/mole. Calculate the value of A//0. 

The enthalpy of combustion of rhombic sulfur is -70.96 kcal/mole. The enthalpy of combustion of monoclinic sulfur is -70.88 kcal/mole. Calculate the standard enthalpy and entropy of transition from rhombic to monoclinic sulfur. 

The AG° values for the hydrolysis of any P - O - P bond of ATP, inorganic pyrophosphate, or any acyl CoA thiolester are all about -34 kj / mole, while the corresponding figure for the hydrolysis of a mixed carboxylic phosphate anhydride is about -55 kj / mole. Calculate the value of AG° for the following reaction describing the activation of fatty acids to the fatty acyl adenylate. 

Exercise 4-10 a. Calculate AH° from bond energies for the conversion of 1-hexene to cyclohexane at 25° and from this, with AS0 as —20.7 e.u. per mole, calculate the equilibrium constant Keq from Equation 4-2. For comparison, calculate the equilibrium constant that would be expected if the degrees of disorder of the reactants and the products were equal (i.e., AS0 = 0). b. How large can AS0 be at 25° for a reaction before our 15 kcal rule starts to give incorrect answers ... 

Chemists sometimes need to calculate the volume of gas consumed or produced in a reaction. For example, we might need to know the volume of carbon dioxide produced when a fuel burns or the volume of oxygen needed to react with a given mass of hemoglobin in the red cells of our blood. To answer this kind of question, we have to combine the mole-to-mole calculations of the type described in Section L with the conversion of moles of gas molecules to the volume they occupy (1). 

Fig. 4a. Dependence of the degrees of filling PMA (pPMA) and copolymers AA-MAA (P,) with PVPD oligomer on the total degree of filling of the polymer with oligomer. Content of units AA in copolymers 20 (7), 50 (2), 85 (2, 5), 100 (4) mole % nPVPD 80 1-4), 360 (5). 19 20> b. Dependence of the difference between average complex formation free energies per base mole, calculated by Eq.

The strength of an acid or a base may be determined by either the normality method or by mole calculation as shown below. When normality of one of the reactants is known, the strength of the other reactant can be determined from the following relationship ... 

Problem 4 At 20°C, S02 was permitted to distribute between 200 c.c. of chloroform and 75 c.c. water. At equilibrium, the chloroform layer contained 0.14 mole ofS02and water layer 0.05 mole. Calculate the distribution coefficient of S02 between water and chloroform. 

The mole is the chemist s counting unit. Working with the mole should be second nature to students, so let s review grams to mole calculations since they are very important in mass-mass stoichiometry and the balanced equations provides mole ratios not mass ratios. 

Example 5.5 A quantity of 100 molee of a mixture containing 50 mole percant benzene, 25 mole percent toluene, and 25 mole percent p-xylene is to be simply distilled until the residual banzene content in the still is reduced to 1.73 moles. Calculate the material balance for the eeparation. 

Answer Determine the surface area of the water at which the pressure increases sharply. Divide this surface area by the number of lipid molecules on the surface, which is calculated by multiplying the number of moles (calculated from the concentration and the molecular weight) by Avogadro s number. 

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