C6 Flashcards
What is electrolysis?
Splitting up with electricity
What happens during electrolysis?
An electric current is passed through an electrolyte. The ions move towards the electrodes , where they react , and the compound decomposes.
What is an electrolyte
A molten or dissolved ionic compound
What moves towards the anode?
Negative ions which will lose electrons. And so it will be oxidised
What is the positive electrode?
Anode
What is the negative electrode ?
Cathode
What moves towards the cathode ?
Positive ions , which will gain electrons and will be reduced
What happens to the ions when an ionic compound is melted or dissolved?
Ions are free to move in the liquid or solution. These liquid solutions are able to conduct electricity and are called electrolytes.
What happens during the process of electrolysis?
Electrical current passes through electrolytes Causing the ions to move to the electrodes. Positively charged ions move to the negative electrode(cathode) and negatively charged ions move to positive electrode(anode). Ions are discharged at the electrodes producing elements. This is electroylsisn
What happens when a simple ionic compound is electrolysed?
The molten state using inerrt electrolydes , the metal is produced at the cathode and the non metal is produced at the anode. For example lead bromide, lead (metal ) will be produced at the cathode and bromine (non metal ) is produced at the anode.
Why cant an ionic solid be electrolysed?
Ions are in a fixed position and cant move
Why can molten ionic compounds be electrolysed?
Ions are free to move and conduct electricity .
What type of metal can be extracted by electrolysis?
A metal more reactive than carbon. It cant be extracted by reduction with carbon or if metals react with carbon.
Problems with electrolysis as a method of extractions?
Very expensive and Required a lot of energy are used in extraction process to melt compounds and to produce the electrical current
How is aluminium extracted ?
From the ore bauxite by electrolysis. Bauxite contains aluminium oxide
Why is aluminium mixed with cryolite
Has a very high melting point so is mixed with cryolite to lower the melting point
What happens when you separate aluminum oxide by electrolysis ?
Molten mixture contains free ions -so will conduct electricity.positive Al3+ ions are attracted to the negative electrode where they each pick up three electrons and turn into neutral aluminium atoms. These sink to the bottom of the electrolysis tank. Negative O2- ions are attracted to the positive electrode where they each lose 2 electrons. They will form O2 molecules.
What is produced at the positive electrode when aluminium oxide is electrolysed?
Oxygen
What is the anode made from ?
Carbon
Why does the anode need to be replaced?
Reacts with oxygen to form carbon dioxide
What is produced at the negative electrode when aluminum oxide is electrolysed ?
Aluminum
Why do metals attract to the negative electrode?(cathode)
Metals form positive ions so they are attracted to it.
What reaction happens at the negative electrode?(cathode)
Reduction
What type of reaction happens at the positive electrode?(anode)
Oxidation
What is the reduction ionic equation at the cathode?
AL3+ 3e- —> AL
What is the oxidation equation at the anode?
2O2- —-> O2 + 4e-
What is the overall iequation for electrolysis of aluminium oxide?
Aluminium oxide —> aluminium +oxygen
Difference between an electrode and electrolyte?
Electrode is a solid that can conduct electrcity qnr the electrolyte is a liquid that can.
What happens when an aqueous solution is electrolysed using inert electrodes?
Ions are discharged
What effects the ions discharged during electrolysis?
Relative reactivity of its elements involved .
What is produced at the cathode if a metal is more reactive than hydrogen?
Hydrogen
What gas is produced at the anode?
Oxygen is produced unless the sodium contains halide ions and hydroxide ions when the halogen in produced
What happens when an aqueous solution of water molecules break down?
Produces hydrogen ions and hydroxide ions that are discharged .
What type of reaction is happening at the cathode?
Positively charged ions gain electrons and so the reaction is reduction.
What type of reaction happens at the anode?
Negatively charged ions lose electrons and so the reactions are oxidation.
