The conductivity of a 0.1 M KCl solution at 18°C is 1.12 × 10−2 S cm−1. The resistance of this solution in a conductivity cell is found to be 65 Ω. What is the cell constant?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 0.728 cm−1
The cell constant G* (= l/A) of a conductivity cell is found from the resistance R of a solution of known conductivity κ:
\( \displaystyle G^*=\kappa\times R \)
\( \displaystyle G^*=1.12\times10^{-2}\,\mathrm{S\,cm^{-1}}\times65\,\Omega \)
\( \displaystyle G^*=0.728\,\mathrm{cm^{-1}} \)
Since 1 S = 1 Ω−1, the units S and Ω cancel and leave cm−1.