Electrolysis

What is electrolysis?

The passing of an electric current through ionic substances that are molten or in solution to break them down into elements; ions are discharged (they lose/gain electrons) at electrodes to produce these

What is an electrolyte?

The liquid/solution which conducts electricity

What is a cathode?

Cathode is the negative electrode.

What is an anode?

Anode is the positive electrode

What occurs at the cathode during electrolysis?

Reduction occurs at the cathode.

What occurs at the anode during electrolysis?

Oxidation occurs at the anode

In aqueous electrolysis, which element is discharged at the cathode?

The less reactive element discharges at the cathode. Hydrogen is produced unless there is a less reactive metal, in which case the said metal is produced.

In aqueous electrolysis, oxygen is produced at the anode unless what?

Oxygen is produced at the anode unless the solution contains halide ions, in which case halogen molecules are produced.

How is aluminium manufactured?

Aluminium is made through the electrolysis of aluminium oxide and cryolite.

Why is aluminum expensive?

Lots of energy is needed to produce the current in electrolysis which makes the process of manufacturing aluminum expensive.

What are the half equations in the extraction of aluminium?

Al³⁺ + 3e^- ⟶Al (cathode)

2O^2- ⟶O₂ + 4e^- (anode)

Oxygen reacts with C of the anode producing CO₂​

Why is cryolite used in manufacturing of aluminium?

It lowers the melting point of aluminium oxide, reducing energy costs

What are the half equations in electrolysis of the aqueous Na₂SO₄?

2H⁺ + 2e^- → H₂ (cathode)

4OH^- → 2H₂O + O₂ + 4e^- (anode)

What are the half equations in electrolysis of the molten and aqueous KCl? 

Molten: K⁺ + e^- → K (cathode)

2Cl^-→ Cl₂ + 2e^- (anode)

Aqeous: 2H⁺ + 2e^- → H₂ (cathode)

2Cl^- → Cl₂ + 2e^- (anode)

What are the half equations in electrolysis of the aqueous CuBr₂?

Cu²⁺ + 2e^- → Cu (cathode)

2Br^- → Br₂ + 2e^- (anode)