Question

Molar conductivity of ionic solution depends on

• A. Surface area of electrodes
• B. Temperature
• C. Concentration of electrolytes in solution
• D. Distance between electrodes

Answer 1

Answer: (B), (D)

Distance between electrodes

Understanding the term Molar conductivity:

Molar conductivity is defined as the conductivity of the solution of an electrolyte divided by the molar concentration of the electrolyte.

${\Lambda }_m=\frac{\kappa \times 1000}{M}$

Here $M=\text{Molarity of the solution}$

$\kappa =\text{Specific conductance/conductivity}$

${\Lambda }_m=\text{Molar conductivity}$

Dependence of Molar conductivity

Factors on which molar conductivity depends are:

i) Temperature: As temperature increases, mobility of ions increases and thus molar conductivity increases.

ii) Nature of electrolyte : Strong electrolyte gives more number of ions as compared to weak electrolyte. As number of ions increases, value of molar conductivity also increases.

iii) Concentration : As concentration increases, the number of ions increases, and consequently the conductivity increases. But due to increase in crowding of ions molar conductivity decreases.

For molar conductivity, the dimensions of electrodes are fixed due to which molar conductivity does not depend on length of electrodes and surface area of electrodes.

Thus, molar conductivity depends on temperature and concentration of electrolyte but it is independent of length and surface of electrodes.

Hence, the correct options are (a) and (b).