NEETChemistryElectrochemistry
Consider the theoretical plots of molar conductivity ( _ m ) versus c for aqueous solutions of NaCl , KCl , and CaCl ₂ at 298 K . Which of the following statements is correct?
Options
- AThe plots for NaCl and CaCl ₂ are parallel to each other because both contain chloride ions.
- BThe plots for NaCl and KCl have the same intercept on the y-axis because they are the same type of electrolyte
- CThe plots for NaCl and KCl are parallel to each other, but they have different intercepts on the y-axis.
- DThe plots for all three electrolytes have the same slope because they are all strong electrolytes.
Correct answer
C. The plots for NaCl and KCl are parallel to each other, but they have different intercepts on the y-axis.
Step-by-step solution
According to the Debye-Hückel-Onsager equation, _ m = _ m ^ - A c . The slope of the plot is - A . The value of the constant 'A' depends on the type of electrolyte (charges on the cation and anion). NaCl and KCl are both 1-1 electrolytes, so they have the same value of 'A'. Thus, their plots will have the same slope and be parallel to each other. The intercept on the y-axis is the limiting molar conductivity ( _ m ^ ). According to Kohlrausch's law, _ m ^ depends on the specific limiting ionic conductivities of the