Understanding Electrolysis for Metal Extraction

What is the primary method used to extract reactive metals from their oxides?

• Distillation

• Hydrolysis

• Electrolysis

• Reduction with carbon

Answer explanation

The primary method used to extract reactive metals from their oxides is electrolysis, where electricity is used to break down the metal oxide into its pure form.

Which of the following metals can be extracted by reduction with carbon?

• Aluminium

• Copper

• Sodium

• Potassium

Answer explanation

Copper can be extracted by reduction with carbon because it is less reactive than carbon, allowing carbon to displace it in the extraction process.

Why is electrolysis considered expensive for metal extraction?

• It requires a lot of energy

• It is labor-intensive

• It requires special chemicals

• It produces hazardous waste

Answer explanation

Electrolysis is considered expensive for metal extraction because it requires a lot of energy to separate the metal from its compounds.

What is the role of cryolite in the electrolysis of aluminium oxide?

• It lowers the melting point of aluminium oxide

• It purifies the aluminium oxide

• It increases the electrical conductivity

• It acts as a catalyst

Answer explanation

Cryolite lowers the melting point of aluminium oxide, facilitating the electrolysis process.

What happens to the oxygen ions at the anode during electrolysis?

• They lose electrons

• They gain electrons

• They combine with aluminium

• They remain unchanged

Answer explanation

During electrolysis, oxygen ions at the anode lose electrons to form oxygen gas. This process is essential for the overall reaction to occur.

What is formed at the cathode during the electrolysis of aluminium oxide?

• Oxygen gas

• Aluminium metal

• Hydrogen gas

• Carbon dioxide

Answer explanation

During the electrolysis of aluminium oxide, aluminium metal is formed at the cathode. This is the correct choice as the process involves the reduction of aluminium ions to form the metal.

What mnemonic helps to remember the process of oxidation and reduction?

• LEO GER

• OIL RIG

• RED CAT

• AN OX

Answer explanation

The correct mnemonic to remember the process of oxidation and reduction is OIL RIG, where Oxidation Is Loss (of electrons) and Reduction Is Gain (of electrons).

What is the overall reaction product of electrolyzing aluminium oxide?

• Aluminium and hydrogen

• Aluminium and oxygen

• Aluminium oxide and carbon dioxide

• Aluminium chloride and oxygen

Answer explanation

Electrolyzing aluminium oxide results in the production of aluminium and oxygen as the overall reaction product.

Why do ions need to be free to move for electrolysis to work?

• To enable chemical reactions

• To prevent the formation of solids

• To allow for temperature control

• To ensure electrical conductivity

Answer explanation

Ions need to be free to move for electrolysis to work to ensure electrical conductivity, which is essential for the process to occur.

What is the purpose of mixing aluminium oxide with cryolite?

• To purify the aluminium oxide

• To make it easier to handle

• To lower its melting point

• To increase its volume

Answer explanation

Mixing aluminium oxide with cryolite lowers its melting point by forming a eutectic mixture, making it easier to handle during the extraction process.