Edexcel Electrolysis Quiz

What is an electrolyte?

• A) A solid ionic compound

• B) A liquid that conducts electricity

• C) An ionic compound in the molten state or dissolved in water

• D) A metal that conducts electricity

Answer explanation

An electrolyte is specifically an ionic compound that can conduct electricity when in a molten state or dissolved in water, making option C the correct choice. Options A, B, and D do not accurately define an electrolyte.

What happens during electrolysis?

• A) Heat energy decomposes compounds

• B) Electrical energy from a direct current decomposes electrolytes

• C) Light energy breaks down elements

• D) Sound energy separates ions

Answer explanation

During electrolysis, electrical energy from a direct current is used to decompose electrolytes into their constituent ions, making option B the correct choice. The other options incorrectly attribute different forms of energy.

During electrolysis, where do positively charged ions (cations) move?

• A) To the positively charged anode

• B) To the negatively charged cathode

• C) To the center of the solution

• D) They remain stationary

Answer explanation

During electrolysis, positively charged ions (cations) move towards the negatively charged cathode, where they gain electrons and are reduced. Therefore, the correct answer is B) To the negatively charged cathode.

What is produced at the cathode during the electrolysis of an ionic solution?

• A) Oxygen

• B) Halogen gases

• C) Hydrogen, unless the metal is less reactive

• D) Metal oxides

Answer explanation

During electrolysis of an ionic solution, hydrogen is produced at the cathode unless the metal is less reactive than hydrogen. In that case, the metal would be deposited instead.

What is produced at the anode if the ionic compound contains halide ions?

• A) Oxygen

• B) Hydrogen

• C) Halogen gases

• D) Metal ions

Answer explanation

At the anode, halide ions (like Cl-, Br-) are oxidized to form halogen gases (Cl2, Br2). Therefore, if the ionic compound contains halide ions, the correct answer is C) Halogen gases.

What is produced at the cathode during the electrolysis of copper chloride solution?

• Cl2 (g)

• Cu (s)

• H2 (g)

• O2 (g)

Answer explanation

During the electrolysis of copper chloride solution, copper ions (Cu²⁺) are reduced at the cathode, resulting in the deposition of solid copper (Cu) on the electrode. Therefore, Cu (s) is produced at the cathode.

During the electrolysis of sodium chloride solution, which gas is produced at the anode?

• H2 (g)

• Cl2 (g)

• O2 (g)

• Br2 (l)

Answer explanation

During the electrolysis of sodium chloride solution, chloride ions (Cl-) are oxidized at the anode, producing chlorine gas (Cl2). Therefore, the correct answer is Cl2 (g).

In the electrolysis of water acidified with sulfuric acid, what is produced at the anode?

• H2 (g)

• Cl2 (g)

• O2 (g)

• Br2 (l)

Answer explanation

During the electrolysis of acidified water, water molecules are oxidized at the anode, producing oxygen gas (O2) and hydrogen ions. Therefore, the correct answer is O2 (g).

What is the product at the cathode during the electrolysis of molten lead bromide?

• Pb (s)

• Br2 (l)

• H2 (g)

• Cl2 (g)

Answer explanation

During the electrolysis of molten lead bromide, lead ions (Pb^2+) are reduced at the cathode, forming solid lead (Pb). Therefore, the product at the cathode is Pb (s).

In the context of electrolysis, what do the + ions do?

• Go to the anode

• Go to the cathode

• Remain in solution

• Form a precipitate

Answer explanation

In electrolysis, + ions (cations) are attracted to the cathode, where reduction occurs. This is because the cathode has a negative charge, which draws the positively charged ions towards it.