Question

At 298K, the conductivity of KCl solutions of molarity 0.1, 0.01 and 1.0 M are recorded as X, Y and Z, S cm$^{-1}$ respectively. The correct relation between X, Y and Z is

• A. $X>Y>Z$
• B. $Z>X>Y$
• C. $Y>X>Z$
• D. $X>Z>Y$

Hint:

For strong electrolytes, conductivity generally increases with increasing concentration due to a greater number of charge carriers (ions) in the solution. However, at very high concentrations, ion-ion interactions can reduce the rate of increase. In this range, the simple proportionality holds.

Answer 1

The Correct Option is B

Step 1: Understand the relationship between conductivity and concentration.
Conductivity ($\kappa$) of an electrolytic solution is directly proportional to the concentration of ions present in the solution.
Step 2: Analyze the concentrations of KCl solutions.
The molarities are 0.1 M, 0.01 M, and 1.0 M.
Step 3: Relate the number of ions to molarity.
KCl is a strong electrolyte and dissociates completely into $K^+$ and $Cl^-$ ions. The number of ions is directly proportional to the molarity. 0.01 M KCl has the lowest ion concentration.
0.1 M KCl has an intermediate ion concentration.
1.0 M KCl has the highest ion concentration.
Step 4: Determine the order of conductivity.
Since conductivity increases with the concentration of ions, the order of conductivity will be the same as the order of molarity.
Conductivity of 1.0 M KCl (Z)>Conductivity of 0.1 M KCl (X)>Conductivity of 0.01 M KCl (Y) Therefore, $Z>X>Y$.
Thus, the correct relation is $ \boxed{Z>X>Y} $.