Calculations molecular ratios

Repeat your analysis for tautomeric equilibria between 4-hydroxypyridine and 4-pyridone, 2-hydroxypyrimidine and 2-pyrimidone and 4-hydroxypyrimidine and 4-pyrimidone. For each, identify the favored (lower-energy) tautomer, and then use equation (1) to calculate the ratio of tautomers present at equilibrium. Point out any major differences among the four systems and rationalize what you observe. (Hint Compare dipole moments and electrostatic potential maps of the two pyridones and the two pyrimidones. How are these related to molecular stability )... 

For example, suppose you wanted to calculate the ratio of effusion rates for hydrogen and nitrogen gases. Remember that both are diatomic, so the molecular mass of H2 is 2.016 g/mol and the molecular mass of N2 would be 28.02 g/mol. Substituting into the Graham s law equation ... 

The adsorption of textile dyes on natural sorbents was investigated by various HPLC methods. The chemical structures and calculated molecular areas of the dyes are depicted in Fig. 3.83. Because of their different chemical structures and retention characteristics, the dyes were separated in different columns with different mobile phases. Basic blue 41 (BB41) was determined in an octylsilica column (75 X 4.6 mm i.d.). The mobile phase consisted of methanol-KH2P04-Na2HP04 buffer (pH = 5) in volume ratio 1 1. Acid blue... 

Figure 18.9 Molecular diffusion coefficients in air, Dla, at 25°C for different molecules plotted as a function of (a) their liquid molar volume, V(, (calculated as ratio of molar mass M, to liquid density, p,L), and (b) their molar mass, Mh Data from references reviewed by Fuller et al. (1966) plotted on double-logarithmic scale.

Calculate the ratio A2mT]/A2(M2 ) for each of the three tubes. Why are the three ratios not the same Explain the experimental observation in terms of the molecular structure of DNA. What was the percentage increase in the overall hyperchromic effect Give a qualitative answer regarding the purity of the DNA sample you used. 

Exercise 29-15 Polymerization of methyl 2-methylpropenoate with benzoyl peroxide labeled with 14C in the aromatic ring gives a polymer from which only 57% of the 14C can be removed by vigorous alkaline hydrolysis. Correlation of the 14C content of the original polymer with its molecular weight shows that, on the average, there are 1.27 initiator fragments per polymer molecule. Write mechanism(s) for this polymerization that are in accord with the experimental data, and calculate the ratios of the different initiation and termination reactions. 

To find the multiple, calculate the ratio of the molecular mass to the empirical formula mass ... 

Voyiatzis and Andrikopoulos discuss adding an orientation-sensitive, resonant Raman additive to a polymer mixture prior to drawing in order to calculate molecular orientation continuously. The approach was tested with poly(vinyl chloride) (PVC), isotactic polypropylene (iPP), and poly(vinylidene fluoride) (PVF2). The ratio of a band from the additive to the orientationally insensitive CH2 bending mode at 1435 cm-1 in the polymer was computed. While the addition of such an additive is unreasonable for many industrial processes, the authors note a favorable alternative for industrial PVC samples. 

Furthermore, these workers varied the ethylene pressure at a constant consumption rate and concluded that the pressure of ethylene is totally independent of the value of the molar ratio r = TMEDA -BuLi for a constant alkyllithium concentration. They also reported that the catalyst efficiency (which was based on the observed and calculated molecular weights of polymer, assuming no chain transfer) was on the order of 40-50%. It should be emphasized that without TMEDA the oligomerization of ethylene does not take place, even though the monomer consumption rate and the initiator efficiency are independent of the quantity of TMEDA present in solution. Hay et al. (20, 21) suggested that TMEDA causes dissociation of the n-BuLi hexamer to give an inactive n-BuLi-TMEDA monomer. Further dissociation of this monomeric n-BuLi-TMEDA forms the free, n-BuLi monomer, which is the active species in the oligomerization reaction [Eqs. (9) and (10)]. 

Problem 4 From kinetic equation, calculate the ratio of specific heat at constant pressure to specific heat at constant volume in case ofmonoatomic gases. How does this ratio vary with molecular complexity of the gas ... 

The first nadimide end-capped oligomers were prepared using the unbalanced classical reaction of a dianhydride (BTDA) with an excess of diamine (MDA) and a quantity of nadic anhydride (NA) corresponding to the diamine excess (Fig. 4). The reaction was performed in NMP with a molecular ratio calculated in order to get a Mn of 1300 g mol-1 [12]. However the amic acid intermediate is not stable enough to allow a long term storage of the NMP solution... 

Obtain the Taylor-Prandtl modification of the Reynolds analogy between momentum and heat transfer and give the corresponding analogy for mass transfer. For a particular system a mass transfer coefficient of 8.71 x 10-6 m/s and a heat transfer coefficient of 2730 W/m2K were measured for similar flow conditions. Calculate the ratio of the velocity in the fluid where the laminar sub-layer terminates, to the stream velocity. Molecular diffusivity = 1.5 x 10 9 m2/s. Viscosity = 1 mN s/m2. Density = 1000 kg/m3. Thermal conductivity = 0.48 W/m K. Specific heat capacity = 4.0 kJ/kg K. 

In this paper, a new test reaction is suggested for characterizing the effective pore size of larger pore (12-membered rings or above) molecular sieve materials. Metadiisopropylbenzene is alkylated with propylene and the weight ratio of 1,3,5- to 1,2,4-triisopropylbenzene formed is calculated. This ratio is used to characterize the effective void space size of molecular sieves. 

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