Question

A conductivity cell has been calibrated with a $0.01M$ $1:1$ electrolyte solution (specific conductance $\kappa =1.25\times {10}^{-3}S{cm}^{-1}$) in the cell and the measure resistance was $800\Omega$ at ${25}^{o}C$. The cell constant will be:

• A. $1.02{cm}^{-1}$
• B. $0.102{cm}^{-1}$
• C. $1.00{cm}^{-1}$
• D. $0.5{cm}^{-1}$

Answer 1

The correct option is C $1.00{cm}^{-1}$

Given that

$\kappa =1.25\times {10}^{-3}S{cm}^{-1}$

$\rho =\frac{1}{\kappa }=\frac{1}{1.25\times {10}^{-3}}{S}^{-1}cm$

From $R=\rho \frac{l}{A}$

$800=\frac{1}{1.25\times {10}^{-3}}\times \frac{l}{A}$

(where $\frac{l}{A}=$ cell constant)

$\therefore \frac{l}{A}=800\times 1.25\times {10}^{-3}=1{cm}^{-1}$