Question

Define Kohlraush Law. Describe its application for
weak electrolyte.​

Answer 1

Answer:

ᴋᴏʜʟʀᴀᴜsʜ ʟᴀᴡ:-

◦•●◉✿Kohlrausch's Law: It is proposed by kohlrausch in 1876. "At infinite dilution the molar conductivity of the electrolyte at infinite dilution is the sum of the ionic conductivities of cations and anions, this is called kohlrausch's law".

Mathematically

λ m∞ =xλc∞+yλc∞

λm∞ = molar conductivity of electrolyte

λa∞ = ionic conductivity of anion

λc∞= ionic conductivity of cation

x= number of anions

y= number of cations✿◉●•◦

ᴀᴘᴘʟɪᴄᴀᴛɪᴏɴ ғᴏʀ ᴡᴇᴀᴋ ᴇʟᴇᴄᴛʀᴏʟʏᴛᴇ :-

• Determination of degree of dissociation of weak electrolyte. If at any concentration C the value of molar conductance is λme.

then

a= λme/λm∞

d = degree of dissociation

• Dissociation constant for weak electrolvte.
• Determination of solubility of sparingly soluble salt.
• Determination of ionic product of water.

Answer 2

Answer:

Kohlrausch's law :

The value of molar conductance at infinite dilution is give by the sum of the contributions of ions (Cation and anion)

λ m∞ =xλ+a∞ +yλ−e∞

λ+2 and λ −e

ionic conductance of cation and anion x and y = no. of ions.

Two applications

(i) Calculation of molar conductance at infinite dilution for weak electrolytes

λ m∞ (CH3COOH)=λ∞ CH3+ COOH+λ∞

(ii) Determination of degree of dissociation of weak electrolyte. If at any concentration C the value of molar conductance is λme

then

a= λme/λm∞

d = degree of dissociation

(iii) Dissociation constant for weak electrolvte.

(iv) Determination of solubility of sparingly soluble salt.

(v) Determination of ionic product of Water.