C6- Electrolysis
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Electrolyte
Liquid or solution that contains an ionic compound
How to set up the circuit for electrolysis
Two electrodes with a gap between them, dip into the electrolyte, one connected to positive terminal and one to negative
Electrolysis
The breaking down of ionic substances into new products using an electric current
Positive electrode name and what it attracts? Negative electrode name and what it attracts?
Anode (+) attracts anions (-) Cathode (-) attracts cations (+)
Where do the ions move during electrolysis?
Positively charged ions move to the cathode, while negatively charged ions move to the anode.
What happens when ions reach the electrode? What remains?
They lose their charge and become elements. Gases may be given off or metals deposited
What must ionic compounds be to be electrolysed
Must be molten or aqueous so the ions are free to move
How does electrolysis work?
Current travels through electrodes to electrolyte. Ions in electrolyte complete the circuit. When the ions reach the electrodes they form a neutral atom
What do positive and negative ions need to become neutral?
Positive ions- gain electrons (reduction) Negative ions- lose electrons (oxidation)
What can half equations represent in electrolysis?
What is happening at each electrode
What is produced at the cathode of an aqueous solution in electrolysis?
Metal; if the metal is less reactive than hydrogen or Hydrogen; if the metal is more reactive than hydrogen
What is produced at the anode of an aqueous solution in electrolysis?
Halogen; if the anion is a halide (group 7 ion) or Oxygen; if the anion is from any other group
How do we extract aluminium? Why? What are the products?
-Aluminium oxide is found in the ore bauxite -Need electrolysis, more reactive than carbon -Aluminium oxide is separated from ore, mixed with cryolite to lower the melting point to make it molten -Aluminium forms at cathode and oxygen at anode
Why are the anodes replaced when extracting aluminium?
Oxygen formed at anode reacts with the carbon in the anode. Makes CO2 that burns away anodes so need replacing
Observations for the production of Copper? Silver? Hydrogen? Halogen? Oxygen?
Copper-brown deposit on electrode Silver- silver deposit on electrode Hydrogen- fizzing Halogen- fizzing, bleached litmus paper Oxygen- fizzing
When sodium chloride solution is electrolysed, what 3 products are produced and where?
Hydrogen gas at cathode Chlorine gas at anode Sodium hydroxide solution