electrolysis Flashcards
(22 cards)
what is electrolysis
the breakdown of an ionic compound by the passage of electricity
what is the vessel electrolysis takes place in called
electrolysis cell
what is the electrode
a rod of metal or graphite which leads an electric current to or from an electrolyte
what is an electrolyte
an ionic compound which conducts electricity when molten or dissolved in water
what is an anode
the positive electrode
what is a cathode
the negative electrode
what is an anion
a negative ion
what is a cation
a positive ion
what ion moves to what electrode
cations move to the cathode and anions move to the anode during electrolysis
what happens when inert graphite of platinum electrode are used
metal or hydrogen is formed at the negative electrode (cathode). This is because the ions moving towards the negative electrodes are positively charged.
non-metals other than hydrogen are formed at the positive electrode (anode). This is because the ions moving towards the positive electrode as negatively charged.
electrolysis of molten lead (II) bromide
cathode - lead
anode - bromine
electrolysis of aqueous copper chloride
cathode - copper
anode- chlorine
electrolysis of dilute sulphuric acid
cathode - hydrogen
anode - oxygen
the making of aluminium
aluminium has a very high melting point of 2054 degrees celsius. cryolite is used to reduce the melting point to 700 degrees celsius to make aluminium easier to extract. for electrolysis, the ore is dissolved in a compound. At the anode is oxygen and the cathode is aluminium
purification of copper
used for wiring and making components
the extraction of copper from copper ore is done by reduction with carbon
electrolysis of copper
the positive electrode (the anode) is made of impure copper which is to be purified. The negative electrode (cathode) is a bar of pure copper. The two electrodes are placed in a solution of copper sulphate. copper ions leave the anode and are attracted to the cathode, where they are deposited as copper atoms. The pure copper cathode increases in size and the anode dwindles away. The impurites left behind from the anode forms a sludge beneath it.
what is brine made from
water and sodium chloride
what is the electrolysis of brine used for
to extract chlorine from salt. sodium hydroxide and hydrogen is also obtained from this.
what cannot mix in the electrolysis of brine
chlorine and sodium hydroxide produced in the process have to be separated as they react with each other
uses of chlorine
purification of water
making plastics
sodium hydroxide
making detergents
making paper
hydrogen
making margarine
make fertilisers
