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What is the role of graphite rod in the electrometallurgy of aluminium? |
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Answer» Solution :In the electrometallurgy of aluminium a fused mixture of alumina, CRYOLITE and FLOURSPAR `(CaF_2)` is electrolysed USING graphite as anode and graphite lined iron as cathode. During electrolysis , Al is liberated at the cathode while CO and `CO_2` are liberated at the anode. At cathode: `Al_(mel t)toAl(1)` AT anode: `C_(s)+O^(2-)toCO_(g)+2r^(ɵ)` `C_(s)+2O^(2-)toCO_2+4e^(ɵ)` If instead of graphite, some metal is used as the anode then `O_2` liberated will not only oxidese the metal of the electrode but would also convert some of the Al liberated at the cathod back to `Al_2O_3`. Since graphite is much cheaper than any metal, therefore graphite is used as the anode, thus the ROLE of graphite in electrometallurgy of Al is to PREVENT the liberation of `O_2` at the anode which may otherwise oxidese some of the liberated Al back to `Al_2O_3`. |
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