2.2 - Electrolysis of Molten Compounds

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What happens in the electrolysis of molten compounds?

the metal will be produced at the cathode and the non-metal at the anode

What happens at the anode at the electrolysis of molten lead bromide?

• negative bromide ions are attracted to the anode and lose electrons forming bromine atoms

• two bromine atoms join to form bromine gas

What happens to the bromine ions in the electrolysis of molten lead bromide?

bromine ions are reduced

What is the equation for the electrolysis of molten lead bromide at the anode?

• 2Br^-_(l) → Br₂ (g) + 2e^-

• 2Br-_(l) - 2e^- → Br_2(g)

What happens at the cathode at the electrolysis of molten lead bromide?

Positive lead ions are attracted to the cathode and gain electrons forming lead

What happens to the lead ions in the electrolysis of molten lead bromide?

lead ions are oxidised

What is the equation for the electrolysis of molten lead bromide at the cathode?

Pb²⁺_(l) + 2c^- → Pb_(s)

When do metals have to be extracted from molten compounds?

when the metal is more reactive than carbon so can’t be reduced by it

What is a disadvantage of extracting metals from molten compounds?

expensive because a lot of energy is needed to melt compiunds and produce electricity

What is aluminium ore?

bauxite

What is the formula for bauxite?

Al₂O₃

What is aluminium oxide dissolved in?

cryolite because it lowers the boiling point of bauxite

What happens at the anode in the extraction of aluminium?

• O^2- ions are attracted to the anode and lose two electrons forming oxyggen atoms

• two oxygen atoms join to make oxygen case

What is the equation for the extraction of aluminium at the anode?

• 2O^-2_(l) → O2_(g) + 4e^-

• 2O^-2_(l) - 4e^- → O2_(g)

What causes the anodes to wear away during the extraction of aluminium at the anode?

oxygen produced her reacts with the graphite producing CO₂

What happens at the cathode in the extraction of aluminium?

Al³⁺ ions attracted to the cathode gain 3 electrons

What is the equation for the extraction of aluminium at the cathode?

Al³⁺ (l) + 3e^- → Al (l)