Question

Part A) Electrolysis is performed on a mixture of CuBr(l), AgBr(l), MgBr2(l), and NiBr2(l). Which of the following is produced at the cathode?

• A) Cu(s)
• B) Ag(s)
• C) Mg(s)
• D) Ni(s)
•  

Part B)You are given some ferrous iodide, FeI2 , and are asked to extract the iron through electrolysis. What can be said about the merits of molten versus aqueous FeI2 ?

• A)You'll have to perform electrolysis on the molten salt because you can't get iron metal from electrolysis of the aqueous solution.
• B) You'll have to perform electrolysis of the aqueous solution because you can't get iron metal from electrolysis of the molten salt.
• C) Electrolysis of either the molten or aqueous salt will produce solid iron.
• D) Electrolysis will not produce solid iron regardless of whether the salt is molten or aqueous.

 

Part C) For which of the following aqueous salts will electrolysis produce hydrogen gas and oxygen gas? Check all that apply.

• A) NiI2(aq)
• B) NaF(aq)
• C) NiF2(aq)
• D) NaI(aq)
• E) CuBr(aq)

Answer 1

A)

If electricity is applied to an aqueous salt solution, the anion with the highest oxidation potential will be oxidized, and the cation with the highest reduction potential will be reduced.

In the given compounds, Ag has the highest reduction potential so, it will get deposited on the cathode.

Hence, the element that produced at cathode is \(\operatorname{Ag}(s)\).

 

B)

In the electrolysis, the reduction of water will compete with the reduction of cation, and oxidation of water will compete with the oxidation of anion. So, the reduction reaction with a higher reduction potential will occur at the cathode.

Therefore, electrolysis of either the molten or aqueous salt will produce solid iron.

Hence, option (C) is correct.

 

C)

In the electrolysis of aqueous salt, water is oxidized if water reduction is less than that of the salt.

In the given salts, only NaF has a higher reduction potential than that of water.

Hence, the correct answer is (C).