Electrochemistry
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What happens when an electric current is passed through a molten ionic compound
The compound decomposes - this is called electrolysis
Do molten ionic componds in solution undergo electrolysis (decompositon of of the comound when electricuty is passed thought it.)?
Yes
Define electrolysis
The brakdown of an ionic compound (molten or in aqueous solution) by the passage of electricity.
what is the name of the vessel in which electrolysis takes place?
An electrolysis cell.
What equipment does eletroysis need?
power supply anode (positve electrode) Cathode (negative electrode) Electrolyte (the molten / aqueous soltion of a compound) Beaker
Define an electrorode
A rod of metal or graphite which leads an electric current to or from an electrolyte.
Electrolyte
An ionc compound which conducts electricity when molten or dissolved in water.
Define an anode
A positive electrode
Define a cathode.
A negative electrode.
Define an anion
A negative ion.
Define a cation.
A positive ion.
When molten lead bromide is the electrolyte what forms at the anode and cathode?
Anode: bromine Cathode: lead
When dilute sulphuric acid is the electrolyte what forms at the anode and cathode?
Anode: oxygen Cathode: hydrogen
When concentrated hydrochloric acid is the electrolyte what forms at the anode and cathode?
Anode: chlorine Cathode: hydrogen
When concentrated acqueous sodium chloride is the electrolyte what forms at the anode and cathode?
Anode: chlorine Cathode: hydrogen
When molten zinc chloride is the electrolyte what forms at the anode and cathode?
Anode: chlorine Cathode: zinc
When molten sodium iodide is the electrolyte what forms at the anode and cathode?
Anode: iodine Cathode: sodium
What is an ionic half equation?
An equation balanced by electrons which shows either oxidation or reduction.
Define electroplating
The coating of the surface of one metal with a layer of another by an electrolytic reaction.
Define electrochemical cell
A source of electricalchemical energy where two metals of differnt reactivity dipping into an electrolyte are connected via an external circuit.
What are the equations at the anode and cathode for
Cathode reaction: Pb2+ + 2e- becomes Pb Anode reaction: 2Br- becomes Br2 +2e-
What are the equations at the anode and cathode for concentrated aqueous NaCl?
Cathode reaction: 2H+ + 2e- becomes H2 Anode reaction: 2Cl- becomes Cl2 + 2e-
What are the equations at the naode and cathode for dilute aqueous NaCl?
Cathode reaction: 2H+ + 2e- becomes H2 Anode reaction: 4OH- becomes O2 + 2H2O + 4e-