What is percent dissociation of NH ₄ OH if molar conductance at zero concentration for NH ₄ Cl , NaCl and NaOH are 130,109 and 213 ~S ~cm ^2 ~mol ⁻¹ respectively and molar conductivity of 0.01 M NH ₄ OH is 9.0 ~S ~cm ^2 ~mol ⁻¹ ?

Step-by-step solution

The percent dissociation of NH ₄ OH is determined using conductivity measurements. Kohlrausch's law gives the limiting molar conductivity as ₀( NH ₄ OH ) = ₀( NH ₄ Cl ) + ₀( NaOH ) - ₀( NaCl ) = 130 + 213 - 109 = 234 S cm ^2 mol ⁻¹ . The degree of dissociation relates measured conductivity to infinite dilution: = _m ₀ = 9.0 234 . Percent dissociation is 100 = 900 234 = 100 26 % . This matches option D , 100 26 % .