Question

During the electrolysis of molten lead bromide, which of the following takes place?
A) Bromine is released at the cathode
B) Lead is deposited at the anode
C) Bromine ions gain electrons
D) Lead is deposited at the cathode

Answer 1

Hint: As we know that electrolysis is the process of decomposition of ionic compounds into their elemental forms when a direct electric current is passed through the compound present in an aqueous solution and the cations are reduced at cathode whereas the anions are oxidised at anode.


Complete answer:
As we know that electrolysis is the process of decomposition of ionic compounds into their elemental forms when a direct electric current is passed through the compound present in an aqueous solution where the cations are generally reduced at the cathode and the anions are oxidised at the anode.
Similarly, when molten lead bromide is electrolysed the bromide ions will be oxidised to bromine leading to release of a reddish brown gas and lead is reduced or deposited at the cathode resulting in its elemental form. We can show this with the help of equations at cathode and anode like:
At anode: $2B{r^ - } \to B{r_2}$
At cathode:
$P{b^{2 + }} + 2{e^ - } \to Pb$
And the overall chemical reaction can be shown as:
$Pb + B{r_2} \to PbB{r_2}$
So we can see that lead is deposited at cathode and bromine is released at anode.

And hence, the correct answer is Option B.


Note: Remember that electrolysis process always involves a flow of electron in the electrodes and ions in the electrolyte and there is always reduction and oxidation at cathode and anode respectively where cathode electrode will attract positive ions and anode electrode will attract the negative ions and these ions will be discharged to give the products. And molten compounds can always be electrolysed when they are present in ionic forms as breakdown of ionic bonds takes place to allow the free movement of ions around.