Kohlrausch’s law of independent ion

Conductivity measurements only define the sum of the equivalent ionic conductances no information about their individual values can be derived. However, it is known that the equivalent conductances of ions may differ significantly. According to Kohlrausch s law of independent ion drift, all ions move independent of each other in an infinitely diluted solution. Since the equivalent conductances of ions differ, they contribute differently to the current transport. The contribution of an ionic species i to the total current is called the transport number... 

At very low electrolyte concentrations, each ion of the electrolyte contributes independently to the molar conductivity. For an electrolyte of the form (A2+) (X2- ) , Kohlrausch s law of independent ion migration can be written as ... 

The following method for computing Ae will make this conception clear. As an example the value of A for acetic acid as a function of the ion concentration will be obtained. The computation depends upon two assumptions the evidence for which has been considered in this chapter. The assumptions are (a) aqueous solutions of sodium chloride, sodium acetate and hydrochloric acid are completely dissociated, and (6) at low ion concentrations the equivalent conductance, X, of the ion constituents of strong electrolytes are independent of the nature of the associated ions, i.ethey follow Kohlrausch s law of independent ion migration. Thus if completely dissociated acetic acid were capable of existence the value of its equivalent conductance Afl hac would be in accord with the relation 20 21-22... 

It is of interest to see whether Kohlrausch s law of independent ion migration which has been shown (page 340) to hold accurately for aqueous solutions is also valid for methyl alcohol solutions. Since transference data are not available a test similar to that for water solutions is not yet possible. If, however, limiting equivalent conductances are independent of the ions with which they are associated the differences of, for instance, the limiting conductances of the sodium and lithium salts of an acid HX should be independent of the nature of the radical X, since... 

In calculating conductivities, Kohlrausch s law of independent ion mobilities is assumed to be applicable, so conductivities may be calculated by summing up the equivalent conductivities of the separate anions and cations in the system. 

At the infinite dilution limit (c—>0) the dissociation is complete and the ion mobility only depends on the ion-solvent interactions and file ionic and the molar conductivities reach their infinite dilution values X° and A°, respectively. In fliis limit the Kohlrausch s law of independent ion migration (Kohlrausch, 1898)... 

In calculating conductivihes, Kohlrausch s law of independent ion mobilities is assumed to be applicable, so conduchvihes may be calculated by summing up the equivalent conductances of the separate anions and cahons in the system. In the non-suppressed mode, the solutes are revealed by the decrements in conductivity that they cause when the hydronium ions are replaced by the less conductive sodium and potassium ions ... 

Each ion has its own characteristic mobiUty. The total conductivity of the electrolyte is the sum of the conductivities of the positive and negative ions. This is known as Kohlrausch s Law of Independent Migration of Ions. 

It may be added that Kohlrausch s law does not lead to any method of deducing the contributions of the individual ions. The immediate practical application of Kohlrausch s law of independent contributions of the ions at infinite dilution is a method for deducing the limiting equivalent conductance, A0, of weak electrolytes. This will be illustrated by taking a specific example of a weak electrolyte. 

When the limiting molar conductivities are to be obtained for a series of ions in a given solvent, the first step is to get the limiting molar conductivity of an ion by one of the above methods. Then, the limiting molar conductivities for other ions can be obtained sequentially by applying Kohlrausch s law of independent ionic migration (Section 5.8). 

The A° values are not accessible to direct measurement, but they may be calculated from transport numbers. Kohlrausch s law of independent ionic conductivities states that at low electrolyte concentrations the conductivity is directly proportional to the sum of the n individual ion contributions, that is. 

According to Kohlrausch s law of the independent migration of ions, the total molar conductivity of an electrolyte (made of v+ cations and v anions e.g., v+ = 1 and V = 2 for CaClz in water) can be expressed as the summation of ionic... 

According to Kohlrausch s law of the Independent Migration of Ions the equivalent conductivity at infinite dilution of a cation (/l0+) or an anion (/l0 ) depends only on the nature of the ion and properties of the medium, such as... 

Vectorial Character of Current Kohlrausch s Law of the Independent Migration of Ions... 

This is Kohlrausch s law of the independent migration of ions The equivalent conductivity (at infinite dilution) of an electrolytic solution is the sum of the equivalent conductivities (at infinite dilution) of the ions constituting the electrolyte (Table 4.13). 

It is of interest to note from Table XXXII that the equivalent conductance of the chloride ion is almost the same in all four chloride solutions at equal concentrations, especially in the more dilute solutions. This fact supports the view expressed previously that Kohlrausch s law of the independent migration of ions is applicable to dilute solutions of strong electrolytes at equivalent concentrations, as well as at infinite dilution. 

Kohlrausch established that electrolytic solutions obeyed Ohm s law accurately once the effect of the electrolysis products was eliminated by using high-frequency alternating current. Kjohlrausch also showed from the experimental data that the conductivity of a solution couId "Be mposed of separate contributions from each ion this is known as Kohlrausch s law of the independent migration of ions. 

Kohlrausch s law. Ions have independent migrations, and the conductance of a solution is the sum of the conductances of the anions and cations. 

Equation (31.27) expresses the molar conductivity as the sum of independent contributions f rom each kind of ion present this is Kohlrausch s law it is strictly correct only if the electrolytic solution is infinitely dilute, c = 0. This is not surprising, since the electrically charged ions should exert a mutual influence on each other, especially if they are present in appreciable concentration. Thus, if A°° is the molar conductivity at infinite dilution, then the expression for Kohlrausch s law is... 

Kohlrausch s law If a salt is dissolved in water, the conductivity of the (dilute) solution is the sum of two values - one depending on the positive ions and the other on the negative ions. The law, which depends on the independent migration of ions, was deduced experimentally by the German chemist Friedrich Kohlrausch (1840-1910). 

Kohlrausch s law AlawdevisedbyGermanchemistFriedrichKohlrausch (1840-1910) that states that the conductivily of a dilute solution is equal to the sum of the independent values. That is, the conductivily of a solution is equal to sum of the molar conductivily of the cations and the molar conductivity of the anions. The law is based on the independent migration of the ions and was deduced experimentally. 

Using Kohlrausch s additivity law of the independent migration of ions, single ion limiting conductivities of all other ions can be obtained. 

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