4) A student is required to construct a battery in the form of a galvanic cell using nickel (II) nitrate and cadmium (II

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4) A student is required to construct a battery in the form
of a galvanic cell using nickel (II) nitrate and cadmium (II)
nitrate. Given that a 0.75 M solution of nickel (II) nitrate must
be used, what concentration of cadmium nitrate is required to
achieve a cell voltage of 0.12 V at 25 °C?
Ni2+(aq) + 2e-  Ni(s) Eored = - 0.40 V
Cd2+(aq) + 2e-  Cd(s) Eored = - 0.26 V
(b) Solvent extraction is being used by a student to separate a
naturally occurring triprotic acid, H3A (25g/L) from an organic
solution. The procedure involved shaking 75 mL of the solution with
100 mL of water and allowing the mixture to equilibrate in a
separatory funnel. The aqueous phase was then titrated in
triplicate with 1 M NaOH for which the following titre values were
obtained: 14.40 mL, 12.00 mL, 12.10 mL. Calculate the partition
coefficient of H3A between the organic solvent and water. Molar
mass of the triprotic acid = 321.7 g/mol