Equivalent mixing proportion

The reversal of charge point is thus an equivalence point. Now this reversal of charge point practically coincides with the above mentioned mixing proportion nig (see scheme Fig. 19b) whereby we are justified from now on to denote this mixing proportion as the equivalent mixing proportion of the isohydric series of mixtures. See also the scheme Fig. 19a in which the sign of the charge is indicated aloi the coacervate branch. 

We see that with mixing proportions relatively richer in the positive complex component (G) than the equivalent mixing proportion, the coacervate drops, are charged electrophoretically positive, with mixing proportions relatively richer in the negative complex component (A) are on the other hand charged negatively. 

In Fig. 21 are plotted the. compositions of the coacervates and equilibrium liquids which represent the equivalent mixing proportion in each of the 5 isohydric series of mixtures. 

In Fig. 22 the colloid compositions of coacervate (column 6) and equilibrium liquid (column 7) are plotted as a function of the mixing proportion of the two sols (column 1). Two separate curves result, C for the coacervate, E for the equilibrium liquid. These curves intersect at the equivalent mixing proportion. Here or at any rate nearly here lies the electrophoretic reversal of charge point of the coacervate. 

Since at the equivalent mixing proportion the colloid composition of the coacervate is the same as that of the equilibrium liquid, it is thus also equal to that of the total mixture. The third auxiliary line drawn at an angle of 45° thus also goes through the intersection of the curves C and E. 

At the equivalent mixing proportion the curves C and E intersect, the colloid composition of both is necessarily equal to that in the total mixture. 

The gelatin sol is a solution of gelatin chloride, the gum arabic sol a solution of (mainly) Ca arabinate. If the colloid cations and colloid anions unite with each other in the equivalent mixing proportion, then mutually equivalent amounts of Ca and Cl ions remain over. 

In a discussion of the indifferent salt resistances it also became manifest that iti every isohydric series this is a maximum near the equivalent mixing proportion (near the reversal of charge point) but that this maximum resistance still depends on the pH and at about pH 3.5—3.7 reaches its highest value (see p. 352, Fig. 13). 

One would now expect that the water content of the coacervate is a minimum in every isohydric series of mixtures at the equivalent mixing proportion (reversal of charge point). In Fig. 28 the dry weights, that is to say, the A + G contents, of the coacervates for the various isohydric series of mixtures of Fig. 20 (p. 359) are plotted as a function of the mixing proportion. It is seen from these figures that the expectation is not in general borne out. 

The minimum water content in the isohydric series of mixtures thus lies to the left of the equivalent mixing proportion, i.e. at mixtures which are relatively poorer in gum arabic. 

The reversal of charge points are indicated by arrows. We see that the equivalent mixing proportion lies much more towards the left for the combination G + N than that for the combination G + A. Since the equivalent weight of N is much smaller than that of A (p. 265 Table 1) this is also quite to be expected. 

We can now apply this rule to obtain a verdict concerning the relative magnitude to be expected of the interfacial tensions coacervate/equilibrium liquid in the case of the binary coacervates G + A and G -h N. Naturally the other conditions must be comparable (the same pH, the same salt content of the medium, equivalent mixing proportion of G and A or of G and N, that is to say, at their reversal of charge points). Under these comparable conditions the complex relations in the G + N coacervate are considerably greater than in the G + A coacervate on account of the so much smaller equivalent weight of N than of A (see p. 375). 

According as the pH is chosen lower, the (apparent) equivalent weight of the gelatin decreases and that of the gum arabic increases (decrease of the dissociation of the COOH group) and thus the mixing proportion of the optimum coacervation expressed in % A also increases. 

At the pH, at which the mixing proportion 50% is the equivalent, the C and E curves intersect and this intersection lies necessarily on the horizontal dotted line. 

In Fig. 24 also we encounter two intersecting curves C and E, the intersecting of which lies on the dotted horii ontal line. This intersection lies at that pH at which the mixing proportion of the sols is just the equivalent one. The colloid proportion in coacervate, equilibrium liquid and total mixture is here the same. At other pH s these three are all different. 

At constant mixing proportion this tendency can only be satisfied at one pH value. At the remaining pH values this is not the case but this tendency is manifested by the fact, that from a given total mixture (for example or m ) a coacervate (ci or C5) is formed which lies considerably closer in colloid composition to the equivalent coacervate corresponding to that pH than the total mixture and an equilibrium liquid (ci or t ) which lies appreciably further away from it. 

Let us first examine Fig. 23 on p. 363 in which such a tangent has been drawn. It touches the coacervate branch at or near that pH at which the line connecting coacervate and corresponding equilibrium liquid and produced downwards passes through the corner W, that is to say, at that pH the given mixing proportion of the colloids is also the equivalent one (the reversal of charge point also lies close by). 

Later measurements have established that the equivalent weight of positively charged clupein is in fact much smaller than that of positively charged gelatin. The.intensity of the complex relations each time at the most favourable mixing proportions and pH thus depends both on the negative and on the positive complex partner. 

In this connection we must also remark that the above mentioned formulations are not correct, not even at equivalent ratios of the electrolytes to the left of the arrow, because the neutral salt BC which remains in solution after the double decomposition, still distributed over both coexisting liquids. Thus the formulations are only approximately correct at very low concentrations. When the mixing proportions are not equivalent, the (colloid) salt, which is present in excess, is in addition distributed over both coexisting liquids. 

Conventional TNT-equivalency methods state a proportional relationship between the total quantity of flammable material released or present in the cloud (whether or not mixed within flammability limits) and an equivalent weight of TNT expressing the cloud s explosive power. The value of the proportionality factor—called TNT equivalency, yield factor, or efficiency factor—is directly deduced from damage patterns observed in a large number of major vapor cloud explosion incidents. Over the years, many authorities and companies have developed their own practices for estimating the quantity of flammable material in a cloud, as well as for prescribing values for equivalency, or yield factor. Hence, a survey of the literature reveals a variety of methods. 

Cobalt. Could not be prepd Copper 4CsH5N.Cu(MnC)4)2 violet crysts expld at about 65°. Was prepd by adding a smail quantity of pyridine to an aq soln of AgN03 and KMn04, mixed in equivalent proportions Nickel. 4C5H5N.Ni(Mn04)2 blk pdr very... 

The RIA or RadiolmmunoAssay uses a known quantity of radiolabeled Ag complexed with an equivalent amount of its corresponding Ab. A standard curve is generated with varying amounts of radiolabel Ag. Then the sample to be analyzed, which is nonradioactive, is mixed with the "hot" Ag -Ab complex. The "cold" Ag will displace the "hot" Ag to a degree proportional to its concentration in the solution. This is then compared to the standard curve. 

---