1.

The molar conductance of NzCl varies with the concentration as shown in the following table and all values follows the equation lamda_(m)^(C)=lamda_(m)^(infty)-bsqrt(C) where lamda_(m)^(C)= molar specific conductance lamda_(m)^(infty)= molar specific conductance at infinite dilution C= molar concentration When a cenrtain conductivity cell (C) was filled with 25xx10^(-4)(M) NaCl solution. The resistance of the cell was found to be 1000 ohm At infinite dilution, Conductance of Cl^(-) and SO_(4)^(-2) are 80ohm^(-1)cm^(2)"mole"^(-1) and 160ohm^(-1)cm^(2)"mole"^(-1) respectively. Q. If the cell (C) is filled with 5xx10^(-3)(N)Na_(2)SO_(4) the observed resistance was 400 ohm. what is the molar conductance of Na_(2)SO_(4)

Answer»

`19.25ohm^(-1)cm^(2)"mole"^(-1)`
`96.25ohm^(-1)cm^(2)"mole"^(-1)`
`385ohm^(-1)cm^(2)"mole"^(-1)`
`192.5ohm^(-1)cm^(2)"mole"^(-1)`

SOLUTION :For `Na_(2)SO_(4)` solution
`K=((l)/(a))xx(1)/(R)=(0.1925)/(400)=4.81xx10^(-4)ohm^(-1)cm^(-1)`
`lamda_(m)=(Kxx1000)/(M)=(4.81xx10^(-4)xx1000)/((5)/(2)xx10^(-3))`
`lamda_(m)(Na_(2)SO_(4))=192.4ohm^(-1)cm^(2)"mole"^(-1)`


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