Question

Calculate the resistance of a .15M solution of CaCl₂ measured using electrodes with 1 cm² surface area 10 mm apart

Answer 1

Let us find the conductivity C of the cell,

given length = 10 mm = 1 cm

area = 1 cm^2

C = length / area

    = 1/1

    = 1 S cm-1

molar conductivity = conductivity / concentration

Feeding the values we have,

molar conductivity = 1/0.15

                              = 6.7 Scm^2mol^-1

Let us calculate the specific conductivity k of the cell,

k = molar coductivity x concentration / 1000

= 6.7 c 0.15 / 1000

= 1.005 x 10^-3 Scm^-1

Finally calulate resistance of cell,

Resistance = 1/k

                   = 1 / 1.005 x 10^-3

                   = 995.0 ohm.cm

Therefore, the resistance if the cell is 995 ohm.cm