Electrolysis of Aqueous Sodium Chloride & Dilute Sulfuric Acid
Electrolysis of Aqueous Sodium Chloride & Dilute Sulfuric Acid
Electrolysis of Aqueous Sodium Chloride & Dilute Sulfuric Acid
Aqueous sodium chloride
Brine is a concentrated solution of aqueous sodium chloride
It can be electrolysed using inert electrodes made from platinum or carbon/graphite
When electrolysed, it produces bubbles of gas at both electrodes as chlorine and hydrogen are produced, leaving behind sodium hydroxide solution
These substances all have important industrial uses:
Chlorine is used to make bleach
Hydrogen is used to make margarine
Sodium hydroxide is used to make soap and detergents
Product at the Negative Electrode:
The H+ ions are discharged at the cathode as they are less reactive than sodium ions
The H+ ions gain electrons to form hydrogen gas
Product at the Positive Electrode:
The Cl– ions are discharged at the anode
They lose electrons and chlorine gas forms
The Na+ and OH– ions remain behind and form the NaOH solution
Diagram showing the products of the electrolysis of aqueous sodium chloride
Dilute sulfuric acid
Dilute sulfuric acid can be electrolysed using inert electrodes made from platinum or carbon/graphite
Bubbles of gas are seen at both electrodes
Product at the Negative Electrode
H+ ions are attracted to the cathode, gain electrons and form hydrogen gas
Product at the Positive Electrode
OH- ions are attracted to the anode, lose electrons and form oxygen gas and water
Determining what gas is produced
If the gas produced at the anode relights a glowing splint dipped into a sample of the gas then the gas is oxygen
Diagram showing the test for oxygen gas
If the gas produced at the anode bleaches damp litmus paper then the gas is chlorine
Diagram showing the test for chlorine gas
If the gas produced at the cathode burns with a 'pop' when a sample is lit with a lighted splint then the gas is hydrogen
Diagram showing the test for hydrogen gas