Electrolysis of Sodium Chloride Flashcards
When common salt ([ ]) is dissolved in water and electrolysed, it produces these useful products - [ ], chlorine and [ ]
Sodium chloride
Hydrogen
Sodium hydroxide
[ ] is produced at the -ve electrode
Hydrogen
[ ] is produced at the +ve electrode
chlorine
[ ] are released from the water
H+ ions
What happens at the negative electrode?
2 hydrogen ions accept 2 electrons to become 1 hydrogen molecule
In order to be elctrolysed, sodium chloride is [ ]
In solution
What happens at the positive electrode?
2 chloride ions (Cl-) lose their electrons and become 1 chlorine molecule
What happens to all the other ions (not the ones forming molecules at the electrodes)? Why?
The sodium ions stay in solution because they’re more reactive than hydrogen
Hydroxide ions from water are also left behind. This means that sodium hydroxide (NaOH) is left in the solution
What do half-equations show? What must you make sure of?
Show the reactions at the electrodes.
Make sure the number of electrons is the same for both half-equations
What is the half-equation of for the electrolysis of sodium chloride at the negative electrode?
2H⁺ + 2e⁻ -> H₂
What is the half-equation of for the electrolysis of sodium chloride at the positive electrode?
2Cl⁻ -> Cl₂ + 2e⁻
OR 2Cl⁻ - 2e⁻ -> Cl₂
What is the half-equation of for the electrolysis of molten lead bromide at the negative electrode?
Pb²⁺ + 2e⁻ -> Pb
What is the half-equation of for the electrolysis of molten lead bromide at the positive electrode?
2Br⁻ -> Br₂ + 2e⁻
Give an example of what chlorine can be used for
Production of bleach and plastics
Describe sodium hydroxide (uses)
Very strong alkali and is used widely in the chemical industry eg, to make soap
