Like charge/sign

Beyond infinite dilution, at practical concentrations, ions in solution are sufficiently near each other to interact electrostatically ions of like charge sign repel each other and those of unlike charge sign attract each other. The average distance apart of the ions, Sect. 2.2.1., is consttained by their concentrations ... 

An important point of the electrocapillary curve is its maximum. Such maximum value of y, obtained when q = 0, corresponds to the potential of zero charge (E ). The surface tension is a maximum because on the uncharged surface there is no repulsion between like charges. The charge on the electrode changes its sign after the... 

STEP 2. Determine for each possible pairing of like-signed charges the values of the functions %(/) and E9(j(I) of I by numerical integration or approximation (for details, see Pitzer, 1987, pp. 130-132 Harvie and Weare, 1980). A computer program for this purpose is listed in Appendix 2. The functions are zero for like charges and symmetrical about zero, so only the positive unlike pairings (e.g., 2-1, 3-1, 3-2) need be evaluated. 

Unlike charges attract and like charges repel each other, so there is a high concentration of counterions attracted to the particle surface whilst co-ions (those with the same sign charge as that of the surface) are repelled. Thermal motion, i.e. diffusion, opposes this local concentration gradient so that the counterions are in a diffuse cloud around the particle. Of course particles which have a like charge will also repel each other but the interaction of the particle surfaces will be screened by the counterion clouds between the particles. The interaction potential is a function of the surface potential, i]/o, and the permittivity of the fluid phase, e = r80, where r is the relative permittivity.12,27... 

In many practical solvent extraction systems, one of the two liquids between which the solute distributes is an aqueous solution that contains one or more electrolytes. The distributing solute itself may be an electrolyte. An electrolyte is a substance that is capable of ionic dissociation, and does dissociate at least partly to ions in solution. These ions are likely to be solvated by the solvent (or, in water, to be hydrated) [5]. In addition to ion-solvent interactions, the ions will also interact with one another repulsively, if of the same charge sign, attractively, if of the opposite sign. However, ion-ion interactions may be negligible if the solution is extremely dilute. The electrolyte is made up of... 

An alpha particle undergoes an acceleration due to mutual electric repulsion as soon as it is out of the nucleus and away from the attracting nuclear force. This is because it has the same sign of charge as the nucleus. Like charges repel. 

We thus see that the interaction force P(h) is positive (repulsive) for the interaction between likely charged membranes and negative (attractive) for oppositely charged membranes. It must be stressed that the sign of the interaction force P(h) remains unchanged even when the potential minimum disappears (for the case Zj, Z2 > 0) or even when the surface potential of one of the membranes reverses its sign (for the case Zj > 0 and Z2 < 0). 

Coulomb s law can also be used to calculate the repulsive energy when two like-charged ions are brought together. In this case the calculated energy value will have a positive sign. 

The algebraic signs of q and q determine whether the force is attractive or repulsive. If q and q2 are like charges, they repel F > 0), whereas opposite charges attract F < 0). In our applications to atomic and molecular structure, it is clumsy and unnecessary to carry the constant 47T6o. We will instead write Coulomb s law in gaussian electromagnetic units, whereby... 

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