Question

chemistry doubt electrolysis

Answer 1

$\large \bold{ANSWER \: 1 }$

A strip of copper is placed in colourless solution of :-

▶$\bold{KNO_3}$

▶$\bold{AgNO_3}$

▶$\bold{Zn(NO_3)_2}$

▶$\bold{Ca(NO_3)_2}$

Copper will replace Ag(silver) from $\bold{AgNO_3}$ solution .

The following reaction is a displacement reaction because, Ag is displaced by Cu.

$\large \bold{ANSWER \:2 }$

▶$\large \bold{REASON}$

Copper lies above Ag(silver) in reactivity series, which means copper is more reactive than silver. If a metal in a compound is reacted with a metal which lies above it in reactivity series, the second metal will displace first one. So, copper displaces silver. So, copper nitrate is formed $\bold{Cu(NO_3)_2}$.

▶$\bold{REACTIVITY \: SERIES}$

▶$\bold{K}$

▶$\bold{Na}$

▶$\bold{Ca}$

▶$\bold{Mg}$

▶$\bold{Al}$

▶$\bold{Zn}$

▶$\bold{Fe}$

▶$\bold{Pb}$

▶$\bold{H}$

▶$\bold{Cu}$

▶$\bold{Ag}$

▶$\bold{Pt}$

▶$\bold{Au}$

$\large \bold{ANSWER \: 3 }$

Blue solution obtained filtered and electrolyzed by Pt electrode.

Electrolyte:-

▶$\bold{Cu(NO_3)_2}$

Ions

▶$\bold{Cu(NO_3)_2 = Cu^{+2} + (NO_3)^{-2}}$

◼$\bold{At \: Anode }$

▶${(NO_3)^{-2} }$ migrates toward anode and gets oxidised.

▶${2 (NO_3)^{-2} - 4e^{-1} \longrightarrow 3(NO_2)}$

◼$\bold{At \: Cathode}$

▶${(Cu)^{-2} }$ migrates toward cathode and gets reduced .

▶${2 (Cu)^{+2} + 4e^{-1} \longrightarrow 2Cu }$

$\large \bold{ANSWER \: 4 }$

◼$\bold{At \: Anode }$

A reddish-brown gas nitrogen dioxide evolves from anode.

◼$\bold{At \: Cathode}$

A pinkish brown metal copper is deposed at cathode.