Q21.87P - Chemistry: Molecular Nature Of Matter And Change

Question

In the electrolysis of molten NaBr,

 (a) What product forms at the anode?

 (b) What product forms at the cathode?

Step-by-Step Solution

Answer

(a) bromine

(b) sodium

Step 1: To find the product forms at the anode

$\text{NaBr}\to {\text{Na}}^{+}+{\text{Br}}^{-}$

(a) In electrolysis of molten salts, the anion turns into a free element. Anions form free elements in the anode. In molten ${\text{NaBr ,the anion is Br}}^{\text{-}}\text{.}$

${\text{2Br}}^{\text{-}}\to {\text{2e}}^{\text{-}}{\text{+Br}}_{\text{2(g)}}$

Hence This   ${\text{Br}}^{\text{-}}{\text{ turns into Br}}_{\text{2(g)}}$

Step 2: To find the product forms at the cathode

(b) In electrolysis of molten salts, the cation turns into a free element. Cations form free elements in the cathode. In molten ${\text{NaBr,Na}}^{\text{+}}\text{ is the cation.}$

${\text{2Na}}^{\text{+}}{\text{+2e}}^{\text{-}}\to {\text{2Na}}_{\text{(s)}}$

Hence The ${\text{Na}}^{+}$ ions turn into sodium metal.