The specific conductance of \( 0.0025 \, \text{M} \) acetic acid is \( 5 \times 10^{-5} \, \text{S cm}^{-1} \) at a certain temperature. The dissociation constant of acetic acid is ______ \( \times 10^{-7} \). (Nearest integer) Consider limiting molar conductivity of \( \mathrm{CH_3COOH} \) as \( 400 \, \text{S cm}^2 \, \text{mol}^{-1} \).
