Question

The pair of electrolytes that posses same value for the constant (A) in the Debye - Huckel - Onsagar equation, $\lambda_m = \lambda^0_m - A\sqrt{C}$ is

• A. $MgSO_4, NaSO_4$
• B. $NH_4Cl, NaBr$
• C. $NaBr, MgSO_4$
• D. $NaCl, CaCl_2$

Answer 1

Answer: (B)

$NH_4Cl, NaBr$

Answer 2

The value of the constant $A$ in the Debye $-$ Huckel -Onsager equation, $\lambda_{ m }=$ $\lambda_{m}^{0}-A \sqrt{C}$ depends on temperature, charges of the ions, the dielectric constant of the solvent and also the viscosity of the solvent. Here, since we are not given the solvent, we will assume that the solvent is the same for each case. Here, the deciding factor is the charge on the ions. Again, in $NH _{4} Cl$ and $NaBr$, the charges on the ions are the same. Hence the pair of electrolytes that will possess the same value for the constant (A) will be $NH _{4} Cl , NaBr$.