1i) Electrolysis

An electric current is the flow of electrons or ions. Covalent compounds can not conduct electricity because they make bonds by sharing electrons which means that they don't have any charge carriers that are free to move.

Electrolytes are liquids that conduct electricity:

Telling the difference between electrolytes and non-electrolytes:

When you place a conductivity probe in an electrolyte, the current flows through the circuit so you can measure its conductivity. When you place a conductivity probe in a non-electrolyte, no currents flow so the reading would be zero conductivity.

Another way of determining would be setting up an electrolytic cell, if the substance will undergo electrolysis then it is an electrolyte.

Electrolysis is when an electric current is passed through an ionic substance that's molten or in solution and it breaks down into a new substance(s). It is free electrons which conduct the electricity.

Example of Electrolysis is Molten Lead (II)Bromide or PbBr₂

Ion present: Pb²⁺ and Br^-

Ion attraction to electrode:

Cathode (-) Pb²⁺

Anode (+) Br^-

Half Equations of the electrodes show what is happening at each stage:

Cathode: Pb²⁺ + 2e^- → Pb

Anode: 2Br- → Br₂ + 2e^-

Electrolysis of aqueous solutions:

As well as the ions from the ionic compound there will be hydrogen ion (H+) and hydroxide ion (OH-) from the water

At the Cathode H+ ions or metal ions (if the metal is less reactive than hydrogen) are present

At the Anode OH- ions or a halide ion when they are in the experiment are present.

Examples:

Sulfuric Acid-

Contains three ions: SO₄^2-, H+ and OH-

Cathode (-) Hydrogen gas is produced:

half equation is 2H+ + 2e^- → H₂

Anode (+) Oxygen and water is produced:

half equation is 4OH- → 2H2O + 4e-

Copper (II) Sulfate-

Contains three ions: Cu²⁺, SO₄^2-, H+ and OH-

Cathode (-) Copper metal is produced:

half equation is Cu²⁺ +2e^- → Cu

Anode (+) Oxygen and water is produced:

half equation is 4OH^- → 2H₂O + 4e^-

Coulombs and Faradays are amounts of electricity:

• one amp flowing for a second means a charge of one coloumb has moved
• Q (charge) = I (Current) x t (Time)
• 96000 coulombs is called one faraday
• One faraday (F) contains one mole of electrons