Hseb Notes - Definition terms of Electrolysis

Electrolysis

(a)    Conductors

They are solid substances except mercury that allow electric current to pass through them. For example metals like copper and aluminium, and non-metal like graphite (carbon)

(b)   Non-conductors 

They are solid or liquid substances that do not allow an electric current to pass through them. For example diamond (carbon), rubber/plastics, benzene, dry wood etc.

(c)    Electrolysis 

It is the decomposition of an electrolyte by passage of electric current through it

(d)   Electrolyte   

It Is a compound which when in solution or in molten state conducts an electric current and is decomposed by it.

Strong electrolyte  

It is one that is completely ionized when in solution or molten form. Examples include sodium chloride solution, dilute hydrochloric acid and sodium hydroxide solution

Weak electrolyte 

It is one that is partially ionized when in solution or molten form. Examples include ammonia solution, ethanoic acid solution and water.

(e)    Non- electrolyte

It is a compound which when it in solution or molten state does not conduct electricity. Non-electrolytes include sugar solution, alcohol and urea.

(f)    Electrodes

They are two pieces of metal or graphite rods by which electrons enter and or leave an electrolyte.

(g) Anode  

It is the positively charged electrode by which electrons leave the electrolyte.

(h) Cathode 

It is the negatively charged electrode by which the electrons enter the electrolyte.

(i) Anion 

It is a negatively charged ion that moves to the anode during electrolysis.

(j) Cation 

It is a positively charged ion that moves to the cathode during electrolysis.

(k) Electroplating 

It is the coating of one metal with another by the process of electrolysis.

(l) Faraday’s laws of electrolysis

The two laws are

·         The mass of a substance liberated during electrolysis is directly proportional to the quantity of electricity passed.

·         When the same quantity of electricity is passed through different electrolytes, the amount of the substances liberated in moles is inversely proportional to the charges on their ions.