Electrolysis Flashcards
What does electrolysis mean and what happens?
Electrolysis means splitting up with electricity.
1) During electrolysis, an electric current is passed through an electrolyte (a molten or dissolved ionic compound). The ions move towards the electrodes, where they react, and the compound decomposes.
2) The positive ions in the electrolyte will move towards the cathode (-ve electrode) and gain electrons (they are reduced).
3) The negative ions in the electrolyte will move towards the anode (+ve electrode) and lose electrons (they are oxidized).
4) This creates a flow of charge through the electrolyte as ions travel to the electrodes.
5) As ions gain or lose electrons, they form the uncharged element and are discharged from the electrolytes.
Why can’t metal ores be extracted in solid form?
Because ionic solid’s ions are fixed in position and can’t move, however molten ionic compounds can be electrolysed because the ions can move freely and conduct electricity.
Where are metals made into pure metals and where are non-metals made into pure non-metals?
Because when metals and non-metals are in ionic compounds, metals give electrons to non-metals leaving metals with a positive charge and non-metals with a negative charge, this means that during electrolysis, metals are attracted to the cathode because positive and negative attract and so do negative and positive. So the pure metal is formed at the cathode and the pure non-metal is formed at the anode.
How are metals extracted from their ores using electrolysis?
If a metal is too reactive to be reduce with carbon or reacts with carbon the electrolysis is used however electrolysis uses a lot of energy.
1) Aluminium is extracted from the ore bauxite by electrolysis. Bauxite contain aluminium oxide
2) Aluminium oxide has a very high melting temperature so it;s mixed with cryolite to lower the melting point/
3) The molten mixture contain free ions - so it’ll conduct electricity
4) The positive Al3+ ions are attracted to the negative electrode where they each pick up three electrons and turn into neutral aluminium atoms. These then sink to the bottom of the electrolysis tank.
5) The negative O2- ions are attracted to the positive electrode where they each lose two electrons. The neutral oxygen atoms will then combine to form O2 molecules.
