A 0.020 mol L ⁻¹ solution of a weak base NH ₄ OH is 5 % dissociated at 298 K . If the limiting ionic conductivities of NH ₄^+ and OH ^- ions are 73.4 S cm ^2 mol ⁻¹ and 198.6 S cm ^2 mol ⁻¹ respectively, what is the molar conductivity of the solution?

Step-by-step solution

Limiting molar conductivity of the weak base NH ₄ OH is given by Kohlrausch's law: _m^ = ^ ( NH ₄^+) + ^ ( OH ^-) _m^ = 73.4 + 198.6 = 272.0 S cm ^2 mol ⁻¹ Degree of dissociation, = 5 100 = 0.05 Since = _m _m^ , the molar conductivity is: _m = _m^ _m = 0.05 272.0 = 13.6 S cm ^2 mol ⁻¹ Answer: 13.6 S cm ^2 mol ⁻¹