--%>
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 : Explain reactions of carbonyl oxygen

    In these reaction oxygen atom of carbonyl group is replaced by either one divalent group or two monovalent groups. Reaction by ammonia derivatives: aldehydes and ketones react with a number of ammonia derivatives such as hydroxylaminem hydrazine, semicarbazide etc. in weak acidic medium.

    		•
  • Q : Hybridization Atomic orbitals can be

    Atomic orbitals can be combined, in a process called hybridization, to describe the bonding in polyatomic molecules. Descriptions of the bonding in CH4 can be used to illustrate the valence bond procedure. We must arrive a

    		•
  • Q : Problem on mole fraction of glucose

    Provide solution of this question. While 1.80gm glucose dissolve in 90 of H2O , the mole fraction of glucose is: (a) 0.00399 (b) 0.00199 (c) 0.0199 (d) 0.998

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

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

    		•
  • Q : Explain methods for industrial

    The important methods for the preparation of alcohol on large-scale are given below:    

    		•
  • Q : Solubility of a gas The solubility of a

    The solubility of a gas in water depends on: (a) Nature of the gas (b) Temperature (c) Pressure of the gas (d) All of the above. Can someone help me in finding out the right answer.

    		•
  • Q : Explain polyhalogen compounds with

    Carbon compounds containing more than one halogen atom are called polyhalogen compounds. Most of these compounds are valuable in industry and agriculture. Some important polyhalogen compounds are described as follows:

    Q : Finding strength of HCL solution Can

    Can someone please help me in getting through this problem. 1.0 gm of pure calcium carbonate was found to require 50 ml of dilute  HCL for complete reaction. The strength of the HCL  solution is given by: (a) 4 N  (b) 2 N  (c) 0.4 N  (d) 0.2 N

    		•
  • Q : Value of molar solution Select the

    Select the right answer of the question. Molar solution contains: (a)1000g of solute (b)1000g of solvent (c)1 litre of solvent (d)1 litre of solution

    		•
  • Q : Explain gels and its various categories.

    Certain sols have the property of setting to a semi-solid, jelly-like form by enclosing the entire amount of liquid within itself when they are present at high concentrations. This process is called gelation and colloidal systems with jelly-like appearance are known as gels. Some common examples

    		•