Predict the products of electrolysis in each of the following :
An aqueous solution of AgNO3 with silver electrodes
An aqueous solution of AgNO3 with platinum electrodes
A dilute solution of H2SO4 with platinum electrodes.
An aqueous solution of CuCl2 with platinum electrodes.
An aqueous solution of AgNO3 with silver electrodes.
In aqueous solution, ionisation of AgNO3 and H2O takes place.
AgNO3(s)(aq)⇌Ag+(aq)+NO−3(aq)
H2O(l)⇌H+(aq)+OH−(aq)
At cathode Ag+ ions has less discharge potential than H+ ions so silver will be deposited at cathode.
Ag+(aq)+e−→Ag(s)
at anode An equivalent amount of silver will be oxidised to Ag^+ ions by releasing electrons
Ag(s)→Ag−(aq)+e−
Ag anode is attaked by NO−3 ions, so it will also produce Ag+ in the solution
An aqueous solution AgNO3 with platinum electrodes. In aqueous solution ionisation of AgNO3 and H2O occurs
AgNO3(s)(Aq)⇌Ag+(aq)+NO−3(aq)H2O(l)⇌H+(aq)+OH−(aq)
As platinum electrodes are non-attackable electrodes, they will not be reacted upon by NO−3 ions.
At cathode Ag will be deposited at cathode.
Ag+(aq)+e−→Ag(s)
At anode Out of NO−3 and OH− ions, only OH− ions will be oxidised (due to less discharge potential) preferentially and NO−3 ions will remain in the solution.
OH−(aq)→OH+e−4OH→2H2O(l)+O2(g)
So, oxygen gas is produced at anode. The solution remains acidic due to the presence of HNO3.
H+(aq)+NO−3(aq)⇌HNO3(aq)
A dilute solution of H2SO4 with platinum elections.
Both H2SO4 and water ionise in the solution
H2SO4(aq)⇌2H+(aq)+SO2−4(aq)H2O(l)⇌2H+(aq)+OH−(aq)
At cathode H+ ioins will be reduced and hydrogen gas is produced at cathode.
H+(aq)+e−→H(g)H(g)+H(g)→H2(g)
At anode OH− ions will be released preferentially and not SO−4 ions due to less discharge potential.
OH−(aq)→OH+e−4OH→2H2O(l)+O2(g)
Oxygen gas is produced at anode.
Oxygen gas is produced at anode.
Solution will be acidic and will contain H2SO4
An aqueous solution of CuCl2 with platinum electrodes. Both CuCl2 and water ionise as usual.
CuCl2(aq)⇌Cu2+(aq)+2Cl−(aq)H2O(l)⇌2H+(aq)+OH−(aq)
At cathode Cu2+ ions will be reduced preferentially due to less discharge potential than H+ ions.
Cu2+(aq)+2e−→Cu(s)
Copper metal is deposited at cathode.
At anode Cl− ions will be discharged in preference to OH− ions and chlorine gas is produced at anode.
Cl−(aq)→Cl(g)+e−Cl(g)+Cl(g)→Cl2(g)