c6. electrolysis Flashcards
When can an ionic compound conduct electricity?
When it is melted or dissolved
What is an electrolyte?
A liquid or solution that is able to conduct electricity
What happens when an electric current is passed through an electrolyte?
The ions move to the electrodes
What is the cathode?
Negative electrode
What is a anode?
A positive electrode
Which electrode are positive ions attracted to?
Negative electrode
Which electrodes are negative ions attracted to?
Positive electrode
What happens at the electrode?
The ions are discharged at the electrodes producing elements
What happens when a simple ionic compound is electrolysed?
The metal forms at the acid and the nonmetal is produced at the anode
When is electrolysis used to extract metals?
When the metal is too reactive to be extracted by reduction was carbon or if the metal reacts with carbon
What are the problems of extracting metals using electrolysis?
Large amount of energy are needed to melt the compound and produce the electrical current
How is aluminium extracted using electrolysis?
The aluminium oxide is melted and mixed with cryolite. the aluminium iron move to the negative electrode to make aluminium and oxygen ions move to the positive electrode to react with the carbon electrode and make carbon dioxide
Why is a mixture used as a electrolyte for extraction of aluminium?
The cryolite lowers the melting point of aluminium oxide
Why am I a positive electrode replaced during the electrolysis of aluminium?
The oxygen reacts with the carbon in the electrode burning it away
During the electro of an aqueous solution, what does the ion discharged at the electrode depend on?
The reactivities of the elements involved
What is formed on the negative electrode if the metal is more reactive than hydrogen
Hydrogen
When is oxygen made at a positive electrode?
When the solution does not contain halide ions
What happens at the cathode
Positive ions gain electrons and are reduced
What happens at the anode
Negative electrode lose electrons and oxidises
What is the voltage produced a by cell depended on
The type of electrode and electrolyte
How can a simple cell be made?
By connecting two different metals in contact with electrolyte
What is a battery?
Two or more cells connected together in the series to make a great voltage
When do non-rechargeable batteries run out?
When the chemical reaction within stops because one of the reactants have been used up
How can rechargeable batteries be recharged?
The chemical reactions are reversed when an external electrical current is supplied
What does the reaction in a hydrogen fuel cell involve?
Oxidation of hydrogen to make water
