IG Chem – Electrolysis (II)

Electrolysis involves the decomposition of an ionic compound by the passage of an electric current.

The anode is the negative electrode that attracts positive ions.

The substance being electrolyzed must contain ions that are free to move.

During electrolysis, negative ions move to the cathode and give up electrons.

Lead(II) bromide is ionically bonded and contains Pb²⁺ ions and Br⁻ ions.

The electrolysis of molten lead(II) bromide produces lead at the cathode and bromine at the anode.

When sulfuric acid is electrolyzed, oxygen forms as a colorless gas at the cathode.

The hydroxide ions (OH⁻) are discharged at the anode in preference to the sulfate ions (SO₄²⁻) in dilute sulfuric acid electrolysis.

When concentrated sodium chloride solution is electrolyzed, chlorine forms at the cathode.

In the electrolysis of copper(II) sulfate using copper electrodes, the mass of the anode decreases.

The reactivity series of metals indicates that metals above hydrogen produce hydrogen gas during electrolysis.

Electoplatting involves using electrolysis to coat an object with a thin film of metal.

The concentration of silver ions in the silver nitrate electrolyte remains constant during silver plating.

Hydrogen and oxygen fuel cells produce electricity with only water as the by-product.

In a hydrogen-oxygen fuel cell, the hydrogen gas is pumped onto the anode and oxygen gas onto the cathode.