Salutations to the Bastions of the CS art. To continue:
The apparent movement of the proton is explained as follows. A hydronium ion approaches a chain of water molecules, and under the influence of the electric field between the electrodes, the positive charge travels down the chain. The final result is that a proton is released from the end chain water molecule. In the case of the hydroxyl ion, the hydrogen from the end water molecule shifts, under the influence of the electric field, to the next water molecule in the chain, leaving a free hydroxyl ion. This occurs at each water molecule along the chain until the original hydroxyl ion appears to have been "transported" down the chain without the actual movement of the hydroxyl group. Since the transport of these ions is effected essentially by the shifting of the more mobile electrons, the velocity of these ions will appear much higher than would be expected for the movement of the heavier proton or hydroxyl group. All the movement is virtual, being accomplished by the movement of the lighter electrons. This is also identified with the concept of "hole" movement in semiconductors, which is the virtual movement of electrons leaving an absence of electrons. As the absence of electrons moves, we may also say a proton is moving. At this point it should be recalled that the behavior of an electrolyte in solution depends upon the solvent as well as the solute. The effect of the solvent is explained by noting that the coulombic force between two ions is inversely proportional to the dielectric constant of the solvent. Therefore, in solvents of higher dielectric constants, the ions of the electrolyte experience smaller interactions with one another, and are more free to carry the electrical current. The effect of the solvent on the equivalent conductance at infinite dilution is illustrated by noting that the Ksub0 values for NaCl at 25 degrees are 126.45 in water and 42.5 in ethyl alcohol. In 1834 Faraday explained the conductivity of solutions by stating that electrolytes are dissociated into ions by the application of an electromotive force across electrodes dipping into an electrolytic solution. It was not until 1887 that Arrhenius corrected and elaborated on this idea and proposed his theory of electrolytic dissociation, which states that when an electrolyte is dissolved in a solvent, a portion or all of the molecules of the electrolyte dissociate into ions. The amount of molecules that dissociate varies with the nature of the electrolyte, its concentration and the temperature. Strong electrolytes are completely dissociated in a solvent. These include substances that: 1. Ionize to give a proton in a solvent, such as HCl in water, which Arrhenius called "acids". Note that because of its high charge density, a proton can never exist in the free state in a solvent. 2. Dissociate to give a hydroxyl ion in a solvent, such as sodium hydroxide, which Arrhenius called "bases" (alkali). 3. Salts that yield free cations and anions in some solvent such as water. Weak electrolytes dissociate incompletely in a solvent. These are also acids, bases, and salts. In water. acetic acid is a weak acid, ammonium hydroxide is a weak base, and mercuric chloride is a soluble salt that is incompletely dissociated. If the ions in solution act independently of each other, the fraction of molecules dissociated , called the "degree of dissociation", is equal to the number of ions actually in solution divided by the total number of ions that could form if all the molecules in solution were dissociated. Since the equivalent conductance is proportional to the number of ions in solution, the degree of dissociation is given by alpha = K/Ksub0. This equation can be used to explain the rapid rise in the equivalent conductance of a weak electrolyte as it is diluted. The principal effect causing the rapid rise in the equivalent conductance as the concentration is lowered is that the undissociated acid is dissociating into free ions to a greater extent at the lower concentrations, and there are more ions to do the conducting. --to be continued-- Bless you Bob Lee -- oozing on the muggy shore of the gulf coast l...@fbtc.net -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: silver-list-requ...@eskimo.com -or- silver-digest-requ...@eskimo.com with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: silver-list@eskimo.com Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <mdev...@id.net>
