C6-electrolysis Flashcards
How does electrolysis break down a substance
Using electricity
Ionic compounds can only be electrolysed when they are molten or dissolved in water. Why is this
This is because their ions are then free to move and carry their charge to the electrodes
In electrolysis where do positive and negative ions move to?
Positive ions move to the cathode( negative electrode).
While negative ions move to the anode ( positive electrode)
In electrolysis do the ions move toward the oppositely charged electrodes?
Yes
What happens at the positive electrode( anode)
Negative ions loose their extra electrons so are oxidised
What happens at the negative electrode (cathode)
The positive ions gain electrons so are reduced
In electrolysis what happens in aqueous solutions?
The less reactive element either hydrogen or the metal is usually produced at the cathode
In aqueous solutions what happens to the anode?
Oxygen gas is given off from discharged hydroxide ions produced from water
A halogen produced if the electrolyte is a solution of a halide
From the ore bauxite what is electrolysed in the extraction of aluminium metal
Aluminium oxide
Why is the aluminium oxide mixed with molten cryolite to lower its melting point?
To reduce the energy needed to extract the aluminium
In aluminium and oxygen which electrode do they form at
Aluminium forms at the cathode and oxygen forms at the anode
Why are carbon anodes replaced regularly?
Because they burn away as the oxygen reacts with the hot carbon anodes forming carbon dioxide gas
When you electrolysed sodium chloride solution ( brine) what three products do you get?
Chlorine gas and hydrogen gas given off at the electrodes plus sodium hydroxide solution( an alkali) left in solution
