[Electrochemistry] Electrolytic Cells

numerical value of the Faraday constant, F

9.65 × 10^4 C mol-1

formula of the Faraday constant, F

Avogadro’s constant (mol-1) x electronic charge (C)

charge, Q

current (A) x time (s)

relationship between charge, Q and the Faraday constant, F

Q = F x n(e- transferred)

polarity of electrodes

anode: positive

cathode: negative

type of reactions occurring at the electrodes

anode: oxidation

cathode: reduction

reduction equation of water and Eø value

2H2O + 2e- ⇌ H2 + 2OH-

-0.83V

oxidation equation of water and Eø value

O2 + 4H+ + 4e- ⇌ 2H20

+1.23V

when two or more anions are present in the aqueous electrolyte at similar concentrations, preferential oxidation of the anion or water with the _____________ will generally occur

least positive/most negative Eø

when two or more cations are present in the aqueous electrolyte at similar concentrations, preferential reduction of the cation or water with the _____________ will generally occur

most positive/least negative Eø

the higher the concentration of any aqueous ion in the electrolyte, the _____ likely it will be discharged

more (apply LCP and its effect on E value)

if electrodes are reactive, remember to consider the

oxidation of the electrode metal at the anode

in the electrolytic purification of copper, the cell voltage is adjusted such that…

only copper and metals with less positive Eø than EøCu2+/Cu are preferentially oxised

any metal in the impure alloy that is not oxidised will…

fall to the base of the cell as anode sludge