--%>
Assignment Help - homework help

How to calculate solutions molar conductance?

The contribution of an electrolyte, or an ion electrolyte, is reported as the molar of a conductance.


The definition of the molar conductance is based on the following conductivity cell in which the electrodes are 1 m apart and of sufficient area that the cell holds the amount of solution that contains 1 mol of solute. The conductivity of such a cell is the mole conductance.

A of solution of concentration c, expressed in moles per litre, has a volume in litres per mole of 1/c or a volume in cubic meters of (10-3 m3 l-1)/c. a cell with this volume and electrodes separated by 1 m would be equilivalent to (10-3 m3 l-1)/c unit cells placed alongside each other. The conductivity of such a cell, which is the molar conductance, is given by:

A = 10-3 m3 l-1/c × k

This relation defines the molar conductance in terms of the specific conductance. The concept of the cell holding solution of volume (10-3 m3 l-1)/c is introduced only to suggest the definition of conductance and in practice one uses any convenient conductance cell, measures R, and calculate L = 1/R. with this datum one obtains k= (cell constant) L and finally A.

Many precise measurements of molar conductance were made by Friedrich Kohlausch and his coworkers between about 1860 and 1880. 

On the basis of such data and in the absence of any satisfactory theory about the nature of conduction in these solutions, some variable empirical relations were concluded. It was recognized that for some electrolytes plotting the molar conductance of an electrolyte at a fixed temperature against the square root of the concentration led to the plots which confirmed very closely at the lower concentrations to straight lines. Such plots for new electrolytes are lead to essentially linear plots are now classed as strong electrolytes, and those which seem to approach the dilute solution limit almost tangentially are classed as weak electrolytes.

An important relation can be deduced from extrapolations of the strong electrolyte data to infinite dilution to give what are known as limiting molar of the independent migration of ions. The law is more easily stated and understandable if some later ideas are anticipated and the conductance of an electrolyte at infinite dilution is treated as being made of contributions from the individual ions of the electrolyte. Let v+ be the number of positive ions and v - the number of negative ions implied by the formula of the electrolyte. 

Molar conductances ? in Ω-1 m2 mol-1 in aqueous solution at 25° C (values for c = 0obtained by extrapolation or, for HAc and NH4OH, by a combination of extrapolated values):

c NaCl KCl HCl NaAc CuSO4 H2SO4 HAc NH4OH
0.000 (0.012645) 0.014986 0.042616 0.00910 0.02661 0.08592 0.03907 0.002714
0.0005 (0.012450) 0.014781 0.042274 0.00892 0.02304 0.08262 0.00677 0.0047
0.001 0.012374 0.014695 0.042136 0.00885 0.01666 0.07990 0.00492 0.0034
0.010 0.011851 0.014127 0.041200 0.008376 0.01010 0.06728 0.00163 0.00113
0.100 0.010674 0.012896 0.039132 0.007280 0.00586 0.05016   0.00036
1.00   0.01119 0.03328 0.00491        

   Related Questions in Chemistry

  • Q : What are heterogenous catalysis? Give

    When the catalyst exists in a different phase than that of reactants, it is said to be heterogeneous catalyst, and the catalysis is called heterogeneous catalysis. For example, SO2 can be oxidized to SO3

    		•
  • Q : Question based on strength of solution

    Help me to go through this problem. On dissolving 1 mole of each of the following acids in 1 litre water, the acid which does not give a solution of strength 1N is: (a) HCl (b) Perchloric acid (c) HNO3 (d) Phosphoric acid

    		•
  • Q : Explain Rotational Vibrational Spectra

    The infrared spectrum of gas samples shows the effect of rotational-energy changes along with the vibrational energy change.As we know from the interpretations given to thermodynamic properties of gases, gas molecules are simultaneously rotating and vibrating. It follows that an absor

    		•
  • Q : What do you mean by the term medicine

    What do you mean by the term medicine dropper? Explain briefly?

    		•
  • Q : Problem on equilibrium composition The

    The catalytic dehydrogenation of 1-butene to 1,3-butadiene, C4H8(g) = C4H6(g)+H2(g) is carried out at 900 K and 1 atm.

    Q : Pressure Phase Diagrams The occurrence

    The occurrence of different phases of a one component system can be shown on a pressure temperature. The phases present in a one line system at various temperatures can be conveniently presented on a P- versus-T diagram. An example is pro

    		•
  • Q : Normality of acetic acid Give me answer

    Give me answer of this question. The normality of 10% (weight/volume) acetic acid is: (a)1 N (b)10 N (c)1.7 N (d) 0.83 N

    		•
  • Q : Polyhalogen compounds introduction for

    introduction for polyhalogen compound

    		•
  • Q : Molecular weight of solute Select right

    Select right answer of the question. A dry air is passed through the solution, containing the 10 gm of solute and 90 gm of water and then it pass through pure water. There is the depression in weight of solution wt by 2.5 gm and in weight of pure solvent by 0.05 gm. C

    		•
  • Q : Define the term oxidizing agent Briefly

    Briefly define the term oxidizing agent?

    		•