Electrolysis

Question 1

What is an electrolyte?

Accepted Answer

A molten or dissolved ionic compound that conducts — An electrolyte is an ionic compound, molten or in solution, whose free ions carry the current.

Question 2

At which electrode does reduction take place?

Accepted Answer

Cathode — At the cathode positive ions gain electrons, which is reduction (Reduction Is Gain).

Question 3

Negative ions (anions) move towards the:

Accepted Answer

Anode — Anions are attracted to the positive anode, where they lose electrons (oxidation).

Question 4

Why can a solid ionic compound not be electrolysed?

Accepted Answer

Its ions cannot move — In a solid the ions are fixed in the lattice, so they cannot move to carry current.

Question 5

What is formed at the cathode during electrolysis of molten lead(II) bromide?

Accepted Answer

Lead — Pb²⁺ + 2e⁻ → Pb; lead metal forms at the cathode.

Question 6

The half-equation at the anode for molten PbBr₂ is:

Accepted Answer

2Br⁻ → Br₂ + 2e⁻ — Bromide ions lose electrons (oxidation) at the anode to form bromine.

Question 7

Which gas is produced at the anode when concentrated sodium chloride solution is electrolysed?

Accepted Answer

Chlorine — Concentrated chloride ions are discharged in preference to OH⁻: 2Cl⁻ → Cl₂ + 2e⁻.

Question 8

Oxidation during electrolysis is best described as:

Accepted Answer

Loss of electrons — Oxidation Is Loss of electrons (OIL); it occurs at the anode.

Question 9

In the electrolysis of concentrated NaCl solution, what forms at the cathode?

Accepted Answer

Hydrogen gas — Hydrogen is less reactive than sodium, so H⁺ is discharged: 2H⁺ + 2e⁻ → H₂.

Question 10

The cathode in electrolysis is the electrode connected to the:

Accepted Answer

Negative terminal — The cathode is the negative electrode; it attracts positive ions (cations).