contents

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contents

• Electrolysis of molten compounds
• Electrolysis of solutions
• Electroplating
• Extraction of metals
• Electric cells

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electrolysis of molten compounds

• an electrolyte is an ionic compound that conducts
  electricity molten state or solution in water
• molten ionic compounds and solutions of ionic
  compounds can conduct electricity due to presence
  of mobile ions that can carry current
• electrolysis is the conduction of electricity by
  an electrolyte, leading to its decomposition
• example electrolysis of molten sodium chloride
• inert electrodes (e.g. carbon electrodes) do not
  react in electrolysis

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electrolysis of molten compounds
electrolysis of molten sodium chloride
ammeter to show current flowing
battery

-
carbon anode attracts anions oxidation
carbon cathode attracts cations reduction
molten sodium chloride
porcelain crucible
pipeclay triangle
HEAT STRONGLY
tripod
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electrolysis of molten compounds
electrolysis of molten sodium chloride

• molten sodium chloride contains Na and Cl- ions
• at the cathode, Na ions take in electrons to
  become Na atoms Na ions are discharged

• at the anode, Cl- ions give away electrons to
  become Cl2 Cl- ions are discharged

2Cl-(l) Cl2(g) 2e-

• overall reaction

2NaCl(l) 2Na(l) Cl2(g)
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electrolysis of molten compounds
electrolysis of molten sodium chloride
electrons flow from anode into battery
electrons flow from battery into cathode
sodium metal produced
molecules of chlorine gas produced
sodium atom
sodium ion attracted to cathode
chlorine atom
sodium ion takes electron from cathode
chloride ion gives electron to anode
chloride ion attracted to anode
anode
cathode
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electrolysis of molten compounds
electrolysis of other molten compounds

• when a molten ionic compound is electrolysed,
  metal is produced at the cathode non-metal is
  produced at the anode

Molten Electrolyte Product at Cathode Product at Anode
calcium chloride, CaCl2 calcium, Ca chlorine, Cl2
sodium iodide, NaI sodium, Na iodine, I2
lead(II) oxide, PbO lead, Pb oxygen, O2