Dissolving explanation

Make a numerical estimate, with an explanation of the assumptions involved, of the specific surface area that would be found by (a) a rate of dissolving study, (b) Harkins and Jura, who find that at the adsorption of water vapor is 6.5 cm STP/g (and then proceed with a heat of immersion measurement), and (c) a measurement of the permeability to liquid flow through a compacted plug of the powder. 

In this discussion, entropy factors have been ignored and in certain cases where the difference between lattice energy and hydration energy is small it is the entropy changes which determine whether a substance will or will not dissolve. Each case must be considered individually and the relevant data obtained (see Chapter 3), when irregular behaviour will often be found to have a logical explanation. 

There is a reasonable explanation of the data in Table 17-IV. When a solute dissolves, the solute molecules must be separated from each other and then surrounded by solvent molecules. Furthermore, the solvent molecules must be pushed apart to make room for the solute mole-... 

As an example of the problem of species in solution, consider the case of a solution made by dissolving some potassium chrome alum, KCrfSO s-12H20, in water. On testing, the solution is distinctly acidic. A currently accepted explanation of the observed acidity is based upon the assumption that, in water solution, chromic ion is associated with six H20 molecules in the complex ion, Cr(H20) a. This complex ion can act as a weak acid, dissociating to give a proton (or hydronium ion). Schematically, the dissociation can be represented as the transfer of a proton from one water molecule in the Cr(H20) 3 complex to a neighboring H20 to form a hydronium ion, H30+. Note that removal of a proton from an H20 bound to a Cr+3 leaves an OH- group at that position. The reaction is reversible and comes to equilibrium ... 

For Pond 3513, the cycle of 2 3 8U and 239,2 °pu concentrations in water (filtered with a 0.22y membrane) is out of phase with the cycle of plutonium concentrations in Lake Michigan. In this shallow pond, the concentrations of the two actinides peak in summer and decline in winter. An explanation for this cycle of plutonium is that photosynthetic activity depletes dissolved CO2 which results in an increase in pH and this in turn shifts the oxidation state in favor of Pu(V) which is desorbed from the sediments(26). 

The early field studies revealed that elevated concentrations of fallout plutonium correlated with Increased concentrations of dissolved organic carbon. Experiments at Argonne National Laboratory corroborate this correlation the explanation Is probably that the organic compounds complex Pu(IV), and, hence, decrease the distribution ratio between water and sedlments(27). In these experiments the distribution ratio (Kj) between sediment and natural waters was measured as a function of DOC. Measurements of Kj In both field and laboratory experiments show an unmistakable effect of DOC upon the distribution ratio. Figure 4 shows the Inverse correlation between the K, of plutonium and concentration of DOC. 

The other state variables are the fugacity of dissolved methane in the bulk of the liquid water phase (fb) and the zero, first and second moment of the particle size distribution (p0, Pi, l )- The initial value for the fugacity, fb° is equal to the three phase equilibrium fugacity feq. The initial number of particles, p , or nuclei initially formed was calculated from a mass balance of the amount of gas consumed at the turbidity point. The explanation of the other variables and parameters as well as the initial conditions are described in detail in the reference. The equations are given to illustrate the nature of this parameter estimation problem with five ODEs, one kinetic parameter (K ) and only one measured state variable. 

The following explanation can be provided. With Cu2+ ions there is a tendency for them to be reduced to Cu metal and precipitated on the electrode, which is reflected by a positive standard reduction potential (+ 0.34 V). For Zn metal there is a tendency for it to be oxidized to Zn2+ ions and dissolved in the electrolyte, which is reflected by a negative standard reduction potential (- 0.76 V). In fact, with Zn one could speak of a positive oxidation potential for the electrolyte versus the electrode, as was often done formerly however, some time ago it was agreed internationally that hence forward the potentials must be given for the electrode versus the electrolyte therefore, today lists of electrode potentials in handbooks etc. always refer to the standard reduction potentials (see Appendix) moreover, these now have a direct relationship with the conventional current flow directions. 

Process I —> I should be faster than process N —> N, since the solubility of the dissolving substance will be much greater for the salt than for the nonionized molecule. A similar explanation can be used for (I —> N)>(N —> N) and (I I)>(N N) and... 

Dining the preparation of chloronitromethane by adding portions of dry sodium acz-nitromethanide to chlorine (40 mol of each) dissolved in carbon disulfide, a violent explosion occurred when the addition was half-complete. Similar reactions using bromine had been executed uneventfully many times previously [1], No certain explanation has emerged, but the sodium salt is known to be explosively unstable, and mixtures of carbon disulfide vapour and air are of course extremely flammable and explosive. Contact of the dry salt with traces of chlorine above its carbon disulfide solution may have led to an exotherm and ignition of the vapour-air mixture in the flask [2],... 

To support this hypothesis, the OBC sample can be fractionated by the TREF experiment. TREF fractionation of the OBC, followed by evaluation of the octene content by 13C NMR, reveals the data shown in Fig. 21. For a polymer blend, each molecule dissolves and elutes according to its comonomer content. The results invariably fall on the line in Fig. 21 labeled random copolymer line. The triangles reveal the comonomer content of the TREF fractions from an OBC. At any given temperature, the polymer eluting has much more comonomer than would be expected for a random distribution. The only explanation is that the comonomer is blocked, as expected from the chain shuttling mechanism. The extent of deviation can even be quantified, and a new method was recently invented to determine the block index for a given polyolefin [46],... 

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