Question

The equivalent conductance of NaCl, HCl, and CH₃COONa at infinite dilution are 126.45, 426.16, and 91 ohm^-1cm²eq^-1 respectively at 25°C. The equivalent conductance of acetic acid(at infinite dilution) would be

• A. 461.61 ohm^-1cm²eq^-1
• B. 390.71 ohm^-1cm²eq^-1
• C. cannot be determined from the given data
• D. 208.71 ohm^-1cm²eq^-1

Answer 1

The Correct Option is B

The correct answer is option (B): 390.71 Ω⁻¹cm²eq⁻¹

The reaction involved is: 

CH₃COONa + HCl ⟶ CH₃COOH + NaCl

Using the formula for calculating the equivalent conductivity at infinite dilution:

$\lambda_{eq}^{\infty}(\text{CH}_3\text{COOH}) = \lambda_{eq}^{\infty}(\text{CH}_3\text{COONa}) + \lambda_{eq}^{\infty}(\text{HCl}) - \lambda_{eq}^{\infty}(\text{NaCl})$

Substituting the values:
$\lambda_{eq}^{\infty}(\text{CH}_3\text{COOH}) = 91 + 425.16 - 126.8$

$\lambda_{eq}^{\infty}(\text{CH}_3\text{COOH}) = 390.71 \, \Omega^{-1}\text{cm}^2\text{eq}^{-1}$

λ^∞_eq = Equivalent conductivity at infinite dilution.