The resistance of a solution A is 50 and that of solution B is 100 , both solutions being taken in t — Electrochemistry Chemistry Question
Question
The resistance of a solution A is 50 $\Omega$ and that of solution B is 100 $\Omega$, both solutions being taken in the same conductivity cell. If equal volumes of solution A and B are mixed, what will be the resistance of the mixture using the same cell? Assume that there is no increase in the degree of dissociation of A and B on mixing.
💡 Solution & Explanation
Let the cell constant be $G^*$. Specific conductance $\kappa_A = G^* / 50$ and $\kappa_B = G^* / 100$. When equal volumes are mixed, their individual concentrations are halved, so their specific conductivities are halved. Total conductivity $\kappa_{mix} = \kappa_A/2 + \kappa_B/2 = G^*/100 + G^*/200 = 3G^* / 200$. Resistance $R_{mix} = G^* / \kappa_{mix} = 200 / 3 = 66.67\ \Omega$. Therefore, correct answer is D.