What does cryolite do to the melting point of bauxite?
The alumina must be molten for electrolysis to work,
since the ions are not free to move in the solid state.
Unfortunately, alumina has a high melting point (2040 °C)
and it is not practical to do electrolysis at such a high temperature.
In the middle of the nineteenth century
it was found that alumina dissolved in cryolite.
Cryolite is sodium aluminium fluoride - Na3AlF6.
A solution of alumina in cryolite melts at about 900 °C
and electrolysis is done at about 950 °C.
since the ions are not free to move in the solid state.
Unfortunately, alumina has a high melting point (2040 °C)
and it is not practical to do electrolysis at such a high temperature.
In the middle of the nineteenth century
it was found that alumina dissolved in cryolite.
Cryolite is sodium aluminium fluoride - Na3AlF6.
A solution of alumina in cryolite melts at about 900 °C
and electrolysis is done at about 950 °C.
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