c3.4 Electrolysis Flashcards
what are inert electrodes
they don’t change during electrolysis
usually made from unreactive metals such as copper or platinum.
during the electrolysis of water, what happens at each electrode
hydrogen ions are discharged at the cathode (-) as a gas.
hydroxide ions are discharged at the anode (+), forming water and oxygen in its gas state.
half equation for what happens at the cathode during the electrolysis of water
4H+(aq) + 4e- => 2H2 (g)
this is reduction
half equation for what happens at the anode during the electrolysis of water
4OH- (aq) => 2H20 (l) + O2 (g) +4e-
this is oxidation
during the electrolysis of solutions, when is hydrogen produced
hydrogen is produced unless there are ions from a metal less reactive than hydrogen
during the electrolysis of solutions, when is oxygen produced
oxygen in produced unless there are elements from group 7
Reactivity series
Potassium Sodium Calcium Magnesium Aluminium CARBON Zinc Iron Tin Lead Hydrogen Copper Silver Platinum Gold
What is electroplating
uses non-inert electrodes that can change.
cathode: the object you want to coat
anode: the metal you want to coat the object in
electrolyte: solution containing ions of the coating metal
How can you purify copper
both electrodes are made from copper anode is impure copper cathode is pure copper copper (II) sulfate solution is usually used as the electrolyte. During electrolysis: cathode gains copper anode loses copper any impurities is collected under the anode
what is electrolysis
the process of passing an electric current through a compound, causing a chemical change.
