A1 - Electrolysis of Sodium Chloride Flashcards
What is electrolysis?
The breakdown of a compound using electricity
What is the term used to describe the breakdown of a compound using electricity?
Electrolysis
Why do ionic substances have to be dissolved or molten during electrolysis?
So that the ions are free to move and carry a current
What substances are produced in the electrolysis of molten NaCl?
Sodium (Na) and chlorine (Cl2)
What ions are present in the electrolysis of molten NaCl?
Na+ and Cl−
What is produced at the positive anode in the electrolysis of molten NaCl?
Cl2
Where is Cl2 produced in the electrolysis of molten NaCl?
The positive anode
What is the equation for the formation of Cl2 in the electrolysis of NaCl?
2Cl− → Cl2 + 2e−
What is produced at the negative cathode in the electrolysis of molten NaCl?
Na
Where is Na produced in the electrolysis of molten NaCl?
The negative cathode
What is the equation for the formation of Na in the electrolysis of molten NaCl?
Na+ + e− → Na
What ions are present in the electrolysis of aqueous NaCl (brine)?
Na+, Cl−, H+, and OH−
What is another name for aqueous NaCl?
Brine
What is brine?
Aqueous NaCl
What is produced at the negative cathode in the electrolysis of aqueous NaCl (brine)?
H2
Where is H2 produced in the electrolysis of aqueous NaCl (brine)?
The negative cathode
What is the equation for the formation of H2 in the electrolysis of aqueous NaCl (brine)?
2H+ + 2e− → H2
What is produced at the positive anode in the electrolysis of aqueous NaCl (brine)?
Cl2
Where is Cl2 produced in the electrolysis of aqueous NaCl (brine)?
The positive anode
What is left behind in solution in the electrolysis of aqueous NaCl (brine)?
NaOH
Where is NaOH produced in the electrolysis of aqueous NaCl (brine)?
It is left behind in solution
What is the purpose of using membrane or diaphragm in the electrolysis of aqueous NaCl (brine)?
To keep the Cl2 and H2 products separate as they form an explosive mixture
What type of ions can pass through the diaphragm in the electrolysis of aqueous NaCl (brine)?
All ions can pass through the diaphragm
Which separator allows all ions to pass through?
The diaphragm
What is the disadvantage of using a diaphragm cell for the electrolysis of aqueous NaCl (brine)?
Some Cl− ions pass through the diaphragm and contaminate the NaOH left in solution
What type of ions can pass through the membrane in the electrolysis of aqueous NaCl (brine)?
Only positive ions can pass through the membrane
Which separator only allows positive ions to pass through?
The membrane
What is the advantage of using a membrane cell for the electrolysis of aqueous NaCl (brine)?
Cl− ions can’t pass through the diaphragm so the NaOH left in solution is uncontaminated
