C6: Electrolysis Flashcards
what happens during electrolysis
an ionic compound is broken down using an electrical current
the compound that is broken down by electrolysis is called the
electrolyte
positive electrode is called
anode
negative electrode called
cathode
positively charged ions move to the
cathode
negatively charged ions move to the
anode
what happens to the ions once they reach the electrode
they lose their charge and become elements
what are the two forms electrolytes can be in?
molten or dissolved in water
why do ionic compounds have to be in liquid form?
their ions are then free to move and carry their charge to the electrode
can covalent compounds be electrolysed
not unless they react or ionise in water
with the cathode half equation, which side are the electrons at?
left
what’s produced at the cathode in an aqueous solution
the less reactive element, hydrogen or the metal
what produced at the anode in an aqueous solution?
oxygen, unless a halide is present.
3 uses of aluminium
-car bodies
-planes
-pans
what compound is used in the extraction of aluminium
aluminium oxide (Al2O3)
what ore do we get aluminium oxide from
bauxite
first step of aluminium extraction
separate aluminium oxide from the ore and any impurities
what do we use in aluminium extraction to make it easier
cryolite
what does cryolite do
lowers the boiling point of aluminium
what’s special about the lining of an aluminium electrolysis cell
the lining is a cathode to collect as much molten aluminium.
issues with aluminium electrolysis
-lots of energy, expensive
-could be using fossil fuels.
aluminium extraction: what are the electrodes made of
carbon
what’s the issue with carbon anodes
oxygen reacts with it to form CO2, so they gradually dissolve.
products of the electrolysis of brine
chlorine
hydrogen
sodium hydroxide solution
what is brine also known as
concentrated sodium chloride solution
