Question

Consider four different samples: aqueous LiCl, molten LiCl, aqueous AgCl, and molten AgCl. Current run through each sample produces one of the following products at the cathode: solid lithium, solid silver, or hydrogen gas. Match each sample to its cathodic product.

Drag the appropriate items to their respective bins.

Bin 1) Solid lithium

Bin 2) Solid silver

Bin 3) Hydrogen gas

Answer 1

Answer:

1.Hydrogen gas gets produced in the case of aqueous $LiCl$

2.Solid lithium in the case of molten $LiCl$

3. Solid silver in the cases of molten and aqueous $AgCl$

Explanation:

Lets look at the cases :

• Aqueous $LiCl$ contains $Li^+$ and $Cl^-$ ions , and since its aqueous , it also contains $H^+,OH^-$ ions.

• But we know that , lithium is small in size and has a positive charge. Thus it has high polarizing power. Thus it cannot move easily through water. Even if it does , it reacts with $OH^-$ to form $LiOH$.

      Thus at the cathode :

       $2H^++2e$⇒$H_2$

• Molten $LiCl$ contains only $Li^+,Cl^-$ ions. Thus the product at cathode would be :

        $Li^++e$⇒$Li$

• In case of aqueous $AgCl$ , the electrode potential values are :

⇒$Ag^++e$⇒$Ag$.....0.80V

⇒$H^++e$⇒$\frac{1}{2}H_2$....0.00V

Thus silver gets reduced at the cathode.

• Molten silver chloride contains only silver and chloride ions only. Thus , only solid silver gets deposited at the cathode.