Electrolysis Flashcards
What is Electrolysis?
The process by which a molten ionic substance or solution containing ions (an electrolyte) is decomposed by an electric current
What is an electrode?
A solid (metal) conductor of electricity
What is the cathode? What happens at the cathode?
The NEGATIVE electrode:
- It attracts positive charge
- Known as cations
- The positively-charged cations GAIN electrons
- Became REDUCED
- To form atoms/ molecules (i.e, pure elements)
What is the anode? What happens at the anode?
The POSITIVE electrode:
- It attracts negative charge
- Known as anions
- The negatively-charged anions LOSE electrons
- Become OXIDISED
- To form atoms/ molecules (i.e, pure elements)
What is an electrolyte?
Ionic compounds that are in their molten state or dissolved
In electrolysis, what type of power supply is used? Why?
Direct current must be used
-to ensure current passes in ONE DIRECTION ONLY
What is the difference between the electrolysis of aqueous solutions compared to molten substances?
The electrolysis of aqueous solutions involves 2 SETS OF IONS:
- The ions of the salt that is dissolved in water
- The ions of water itself (H+ and OH-)
During the electrolysis of aqueous solutions, how do you know which set of ions will be oxidised/ reduced?
- The NEGATIVELY charged ions will be attracted to the anode
- The POSITIVELY charged ions will be attracted to the cathode
- If there is more than 1 ion at each electrode whichever ion is more reactive
- will want to REMAIN in their charged/ ionised state;
- The less reactive ion will become the cation/anion and act on the electrode
Write out the reactivity series from MOST to LEAST reactive using an acronym
“Please Stop Like Calling Me A Careless Zebra Instead Try Learning How Copper Saves Gold Plates”
- Potassium
- Sodium
- Lithium
- Calcium
- Magnesium
- Aluminum
- Carbon
- Zinc
- Iron
- Tin
- Lead
- Hydrogen
- Copper
- Silver
- Gold
- Platinum
During the electrolysis of an aqueous solution, what is formed at the anode?
Either the negatively charged ion from the slat OR the OH- ion
- If the aqueous solution contains halide ions, the halogen will be produced at the anode
- If the aqueous solution DOES NOT contain halide ions, the OH- will react to produce O2 at the anode
What is electroplating?
A process that used electrolysis to coat the surface of one metal with another metal
Explain how electrolysis is used to electroplate objects
- The object to be electroplated is always made the negative electrode; to attract the positively charged metal ions
- At the anode, metals will lose electrons and become ions; we put the plating metal on the anode side.
- The electrolyte should also contain the metal ions to be plated
