Using Mole-Based Conversions

Compare and contrast the number of representative particles and the mass of UF6 with the number of representative particles and mass of CC13CF3. Explain any differences 

CC13CF3 is a chlorofluorocarbon responsible for the destruction of the ozone layer in Earth s atmosphere. How many molecules of the liquid are in 1.0 g of CC13CF3  

Lead (Pb) is used to make a number of different alloys. What is the mass of lead present in an alloy containing 0.15 mol of lead  

---

While all three units are commonly used, it is important to note that use of units of type 3, requires knowledge of the solution density to convert these units into those of the other types. In addition, type 3 units must be defined at a particular temperature since the volume of a solution is a function of temperature. The best units to use for solution preparation are mass of solute per mass of solvent. These units have no temperature dependence and solutions can be prepared simply by weighing each species. Conversion among mass (or mole) based units is also simple. Example 1.1 demonstrates conversion of units of all three types. 

Although the conversion of an aldehyde or a ketone to its enol tautomer is not generally a preparative procedure, the reactions do have their preparative aspects. If a full mole of base per mole of ketone is used, the enolate ion (10) is formed and can be isolated (see, e.g., 10-105). When enol ethers or esters are hydrolyzed, the enols initially formed immediately tautomerize to the aldehydes or ketones. In addition, the overall processes (forward plus reverse reactions) are often used for equilibration purposes. When an optically active compound in which the chirality is due to an asymmetric carbon a to a carbonyl group (as in 11) is treated with acid or base, racemization results. If there is another asymmetric center in the molecule. 

Up to 30 % conversion the rate of decomposition determined on the basis of the percent metallic lead precipitated is zero-order. The rate coefficient for the decomposition in solution is 2.43 x 1012 exp(—35,200/I r) mole.sec-1. If reaction (2) is fast compared with reaction (1), kx = 1.22 x 1012 exp(—35,200/RT) mole. sec-1. The rate of decomposition of hexaethyldiplumbane was also studied. Based on spectroscopic observation of the concentration of the reactants, k3 — 5.89 x 1010 exp(—28,500/RT ) mole.sec-1. On the basis of formation of metallic lead, the rate coefficient was 2.44 xlO10 exp(—28,000/HT) mole.sec-1. Therefore, under the conditions used k3 kx and reaction (3) is followed rapidly by reaction (4). 

The film (individual) coefficients of mass transfer can be defined similarly to the film coefficient of heat transfer. A few different driving potentials are used today to define the film coefficients of mass transfer. Some investigators use the mole fraction or molar ratio, but often the concentration difference AC (kg or kmol m ) is used to define the liquid phase coefficient (m while the partial pressure difference A/i (atm) is used to define the gas film coefficient (kmolh m 2 atm ). However, using and A gp of different dimensions is not very convenient. In this book, except for Chapter 15, we shall use the gas phase coefficient (m h" ) and the liquid phase coefficient ki (m h ), both of which are based on the molar concentration difference AC (kmol m ). With such practice, the mass transfer coefficients for both phases have the same simple dimension (L T" ). Conversion between k and is easy, as can be seen from Example 2.4. 

The base members of the series [Mo(N2H)X(dppe)2] (X = F or Br) were obtained initially by treatment of [Mo(N2H2)X(dppe)2]+ (themselves obtained from reaction of [Mo(N2)2(dppe)2] with HX) with exactly one mole of NEt3.138 If an excess of base is used, reaction under N2 regenerates the parent [Mo(N2)2(dppe)2]. They react with acid, primarily to regenerate the hydrazide(2 - ) complexes, and kinetic studies suggest that they are also formed as intermediates during the conversions of coordinated dinitrogen to hydrazide(2 - ).139... 

Because NaOH and Ca(OH)2 are strong bases, they are 100% dissociated and their [OH ] is directly related to their initial concentrations. To calculate the [OH ] in a solution prepared by dissolving CaO, we must first do a mass-to-mole conversion and then use the balanced equation for the reaction of CaO with water to find the number of moles of OH-in the solution. In each case, [H30 + ] = Kw/[OH-] and pH = — log[H30 + ]. 

Another commonly used method for determining the extent of reaction is conversion. Conversion is based on initial and final molar quantities of a reactant. This molar basis can be written in terms of either total moles of reactant or in terms of molar flow rate. In equation form,... 

Carbon conversion efficiency is defined as the experimental number of moles of H2 produced per mole of carbon substrate consumed as a percentage of the theoretical maximum.129 Based on the organic acid substrate used, the theoretical maximum can be calculated according to the Eq. 7, assuming that all of the substrate is used for H2 production ... 

In the above relationship, the left-hand side term, being ratio of two activity coefficient terms is independent of the standard state chosen. The activity coefficient (generally termed /) based on 1 weight percent solution as the standard state, can very well be used. On the right hand side, N or the mole- (or atom-) fraction, would be replaced by weight per cent of solute and the interaction coefficient would have to absorb within it the corresponding conversion factor for composition. In this form, the interaction coefficient is generally represented by the symbol e . 

The weight percents of the individual homologs in each specific-Z series (carbon-number distributions) were calculated from LV/EI/MS molecular-ion intensities assuming constant mole sensitivities for each specific-Z series. An invalid factor was inadvertently used in the previous conversion of the LV/EI/MS carbon-number distributions for the asphaltene neutral fraction to carbon-number distributions based on the total liquid. Consequently, the entries in the LV/EI/MS carbon-number distributions for Z(H), Z(O), and Z(S) asphaltene neutral aromatic compounds in References 35 and 47, the total weight percentages of these specific-Z series in References 35, 47, and 48, and the sums of these latter weight percentages reported in all these references should be multiplied by 0.892. 

---