Question

The resistance of a decinormal solution of a salt occupying a volume between two platinum electrodes 1.80 cm apart and 5.4 cm² in area was found to be 32 ohms.

Calculate the specific and equivalent conductances of the solution.

Answer 1

Given:

Distance between electrodes, l = 1.80 cm

Area of electrodes A = 5.4 cm²

Resistance R = 32 Ω

Concentration = decinormal = 0.1 N

`"Cell constant" = l/A`

= `1.80/5.4`

= 0.333 cm⁻¹

The specific conductance, κ:

`kappa = "Cell constant" xx 1/R`

= `0.333 xx 1/32`

= 0.0104 ohm⁻¹ cm⁻¹

The equivalent conductance, Λ_eq:

`Lambda_"eq" = (kappa xx 1000)/N`

= `(0.0104 xx 1000)/0.1`

= 104 ohm⁻¹ cm² eq⁻¹