Topic 4 Electrochemistry

Electrolysis

Breakdown of ionic compound using electricity

Electrolyte

Ionic substance molten or aqueous that conducts electricity

Electrode

Conductor through which electricity enters or leaves electrolyte

Cathode

Negative electrode where reduction occurs

Anode

Positive electrode where oxidation occurs

Oxidation

Loss of electrons

Reduction

Gain of electrons

Redox reaction

Reaction involving oxidation and reduction

Electrolysis of molten lead bromide

Lead forms at cathode bromine forms at anode

Electrolysis of aqueous sodium chloride

Hydrogen at cathode chlorine at anode if concentrated

Electrolysis of dilute sulfuric acid

Hydrogen at cathode oxygen at anode

Electroplating

Coating object with thin layer of metal using electrolysis

Purification of copper

Impure copper anode pure copper cathode

Reactivity series order

Potassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, tin, lead, copper, silver, gold, platinum

Reason more reactive metals form positive ions more easily

They lose electrons more readily

Displacement reaction

More reactive element displaces less reactive element from compound

Test for hydrogen

Squeaky pop with lighted splint

Test for oxygen

Relights glowing splint

Test for chlorine

Bleaches damp litmus paper