--%>
Assignment Help - homework help

How to calculate solutions ionic mobilities?

Transference numbers and molar conductors can be used to calculate ionic mobilities.

This tables under is giving the transference numbers for positive ions at 25 degree C and the values obtained by extrapolation to infinite dilution:

948_Solution ionic mobilities.png 

Molar ionic conductances and ionic mobilities at infinite dilution and 25 degree C.

1491_Solution ionic mobilities1.png 

Values can now be obtained for the contributions the individual ions of an electrolyte make to the molar conductance. The empirical law of Kohlrausch implies that a infinite dilution the molar conductance can be interpreted in terms of such ionic contributions and that the contributions of an ion are independent of the other ion of the electrolyte. At infinite dilution, therefore, we wrote:

?° = v + λ°+ v- λ°- where 

λ°+ and λ°- are the molar ionic conductors at infinite dilution. Since the transference numbers give the fraction of the total current by each ion, i.e., the fraction of the total conductance that each contributes, we can write;

v+ λ°+ = t°+ ?°  and v- λ°- = t°- ?°  

where t°+ and t°- are the transference numbers extrapolated to infinite dilution. 

Ionic mobilities: consider a cell of the type used to introduce the concept of molar conductance. Such a cell consists of two electrodes 1m apart and of cross-section area A such that an amount of solution that contains 1 mol of electrolyte is held between the electrodes. For an applied voltage ∫, a current I will flow through the cell. These electrical quantities are related, since the conductance of such a cell is the molar conductance of the electrolyte, by:

I = ∫/R or I = ?∫

At infinite dilution the current can be attributed to the independent flow of positive and negative ions, and one can write:

I = ?°∫ = [v+ λ°+ + v- λ°- ] ∫ = v + λ°+ ∫ + v- λ°- ∫ = I+ + I-

   Related Questions in Chemistry

  • Q : What is synthetic rubber and how it

    To meet human needs, scientists have started preparing synthetic rubbers. Besides having similar properties as natural rubbers they are tougher, more flexible and more durable than natural rubber. They are capable of getting stretched to twice its length. Though, it reverts to its original shape

    		•
  • Q : Colligative properties give atleast two

    give atleast two application of following colligative properties

    		•
  • Q : Colligative effect Choose the right

    Choose the right answer from following. Which one of the statements written below concerning properties of solutions, explain a colligative effect: (a) Boiling point of pure water decreases by the addition of ethano (b) Vapour pressure of pure water d

    		•
  • Q : Explain the molecular mass with respect

    During the formation of polymers, different macromolecules have different degree of polymerisation i.e. they have varied chain lengths. Thus, the molecular masses of the individual macromolecules in a particular sample of the polymer are different. Hence, an average value of the molecular mass is

    		•
  • Q : Quantum Mechanical Operators The

    The quantum mechanical methods, illustrated previously by the Schrödinger equation, are extended by the use of operators. Or, w

    		•
  • Q : Vapour pressure of water Give me answer

    Give me answer of this question. 5cm3 of acetone is added to 100cm3 of water, the vapour pressure of water over the solution: (a) It will be equal to the vapour pressure of pure water (b) It will be less than the vapour pressure of pure water

    		•
  • Q : Problem on endothermic or exothermic At

    At low temperatures, mixtures of water and methane can form a hydrate (i.e. a solid containing trapped methane). Hydrates are potentially a very large source of underground trapped methane in the pole regions but are a nuisance when they form in pipelines and block th

    		•
  • Q : Question associated to vapour pressure

    Choose the right answer from following. The vapour pressure lowering caused by the addition of 100 g of sucrose(molecular mass = 342) to 1000 g of water if the vapour pressure of pure water at 25degree C is 23.8 mm Hg: (a)1.25 mm Hg (b) 0.125 mm Hg (c) 1.15 mm H

    		•
  • Q : Molecular weight of substance The

    The boiling point of a solution of 0.11 gm of a substance in 15 gm of ether was found to be 0.1oC higher than that of the pure ether. The molecular weight of the substance will be (Kb = 2.16)       (a) 148 &nbs

    		•
  • Q : Chemical formula of detergent Describe

    Describe the chemical formula of detergent?

    		•