## Shaillee Kaushal is teaching live on Unacademy Plus

XII- 03 Electrochemistry - IV

Equivalent conductance It is defined as the conductance of all the ions produced by one-gram equivalent of an electrolyte in a given solution. It is denoted by Dilute the solution to say 9 cm3 or 9 mL the conductance of solution will be same but specific conductance becomes as it contains 9 cubes. The conductance is also equal to equivalent conductance. Equivalent conductance ^,-9 k In general V volume in mL V-volume in mL Ifthe concentration is 'c' g-equivalent per liter Units S cm2eq1

Molar conductance: It is defined as the conductance of all the ions produced by ionisation of 1 g mole of an electrolyte when present in V ml of solution. It is denoted by - k x 100 Units = Scm2 mol-1 Molecular conductance Equivalent condutance molecular mass Equivalant mass

Effect of dilution on Equivalent conductance: The value of equivalent conductance increases with dilution. This is because degree of ionisation increases with dilution and a large number ofions are produced in solution Solutions which contain large number of ions has more conductance and are called strong electrolytes The number of ions from an electrolytic depends upon the degree of dissociation Potassium chlonde Barium chloride Nickel sulphate Acetic acid

Debey Huckel Onsager Equation To calculate the molar conductance ofstrong elecrolyte Debey Huckel proposedan equation known as the Debey Huckel Onsager equation. According to this equation 0m is the limiting molar condutivity. A is a constant which depends upon the kind of elecrolyte. Strong Electrolyte (KC) Weak Electrolyte (CHCOOH

Kohlrausch's law: At infinite dilution, when dissociation in complete each ion makes a definite contribution towards equivalent conductance ofthe electrolyte irrespective ofthe nature oftheion with which it is associated and the value ofequivalent conductance at infinite dilution for an electrolyte is the sum of contribution ofits constituentions. conductivity of anions. Ac-conductivity of cations. The ionic conductance is proportional to its ionic mobiliies He and Ha are mobilities of cations and anions respectively. When complete dissociation takes place then the degree of dissociation'ox becomes unity Equivalent conductance at given conc Am Equivalent conductance at infinite dilution

Relation between Equivalent and molar conductance at infinite dilution:- BaCl2

(i) Weak electrolytes are not completely ionised when dissolved in a polar medium like water There exists equilibrium between ions and unionized molecules (ii) Concept ofchemical equilibrium and law ofmass action can be applied to ionic equilibrium also AB A+B 0 ABC(1-) 1-0 For weak electrolytes (iii) Degree of ionisation