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The molar conductance of NaCl varies with the concentration as shown in the following table and all values follows the equation. `lambda_(m)^(c)=lambda_(m)^(oo)-bsqrt(C)` where `lambda_(m)^(c)`= molar specific conductance `lambda_(m)^(oo)=` molar specific conductance at infinite dilution C=molar concentration When a certain conductivity cell (C) was filled with 25`xx10^(-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. What is the cell constant of the conductivity cell (C)?A. `0.385 cm^(-1)`B. `3.85 cm^(-1)`C. `38.5 cm^(-1)`D. `0.1925 cm^(-1)` |
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Answer» Correct Answer - D For `25xx10^(-4)(M)` NaCl solution `lambda_m=lambda_m^oo-bsqrtC` `lambda_m=127-10^3(25xx10^(-4))^(1//2)` `lambda_m=127-10^3xx5xx10^(-2)` `lambda_m=77` `lambda=(1000.G.sigma)/M` so, `sigma=(Mlambda)/(1000 G)=(Mlambda)/(1000 G)=(25xx10^(-4)xx77xx1000)/1000=0.1925 cm^(-1)` |
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