Electrolysis Flashcards
What is electrolysis
Use of an electrical current to break down compounds containing ions into their consistuent element
During electrolysis
- negatively charged ions move to ANODE (positive electrode)
- positively charged ions move to the CATHODE (negative electrode)
Oxidation and reduction
- Reduction occurs when positively charged ions gain electrons at the negative electrode
- oxidation occurs when negatively charged ions lose electrons at the Positive electrode
Metals that are more reactive than carbon can be extracted …
From their ores using electrolysis, requires a lot of heat and electricity, so it’s expensive
What’s cryolite and when is t used
- compound of aluminium
- Aluminium is obtained by the electrolysis of aluminium oxide that has been mixed with this
Use of cryolite
-lowers melting point of aluminium oxide, meaning less energy is needed
At the negative electrode (during electrolysis of aqueous solutions):
- hydrogen is produced if the metal is more reactive than hydrogen
- the metal is produced if the metal is less reactive than hydrogen
At the positive electrode (during electrolysis of aqueous solutions):
- oxygen is produced unless solution contains halide ions
- if halide ions are present, then halogen is produced
In the electrolysis of sodium chloride solution:
- hydrogen is released at the negative electrode
- chlorine gas is released at positive electrode
REQ.PRAC of what happens when aqueous solutions are electrolysed using inert electrodes, method
1) set up equipment
2) pass an electric current through the aqueous solution
3) observe products formed at each inert electrode
Hazard: low voltage must be used to prevent electric shock, experiment should only be carried out for a short period of time to prevent exposure to dangerous levels of chlorine gas
