The resistance of a conductivity cell filled with 0.1 mol L-1 KCl solution is 100 . If the resistance of the same cell when filled with 0.02 mol L-1 KCl solution is 520 , calculate the conductivity and molar conductivity of 0.02 mol L-1 KCl solution. The conductivity of 0.1 mol L-1 KCl solution is 1.29x 10-2
-1cm-1
Given that:
Concentration of the KCl solution = 0.1 mol L-1
Resistance of cell filled with 0.1 mol L-1 KCl solution = 100 ohm
Cell constant = G* = conductivity x resistance
1.29x10-2 ohm-1 cm-1 x 100 ohm = 1.29 cm-1 = 129 m-1
Cell constant for a particular conductivity cell is a constant.
Conductivity of 0.02 mol L-1 KCl solution = =0.248 Sm-1
Concentration = 0.02 mol-1
= 1000x 0.02 mol m-3 = 20 mol m-3
Now,
Molar conductivity =
State Faraday's first law of electrolysis. How much charge in terms of Faraday is required for the reduction of 1 mol of Cu2+ to Cu.
Calculate emf of the following cell at 298 K: Mg(s) | Mg2+(0.1 M) || Cu2+ (0.01) | Cu(s)
[Given E0 cell = +2.71 V, 1 F = 96500 C mol-1]
Account for the following:
(i) Mn2+ is more stable than Fe2+ towards oxidation to +3 state.
(ii) The enthalpy of atomization is lowest for Zn in 3d series of the transition elements.
(iii) Actinoid elements show a wide range of oxidation states.
(i) Name the elements of 3d transition series that show a maximum number of oxidation states. Why does this happen?
(ii) Which transition metal of 3d series has positive E0 (M2+/M) value and why?
(iii) Out of Cr3+ and Mn3+, which is a stronger oxidising agent and why?
(iv) Name a member of the lanthanoid series that is well-known to exhibit +2 oxidation state.
(v) Complete the following equation: MnO4- + 8H+ + 5e- -->