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chemistry paper 1 (electrolysis (separation of ionic compounds into…
chemistry paper 1
electrolysis
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+ve ions (metal) go to cathode, -ve (non-metal) go to annode
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when electrodes reached, ions become atoms/molecules
when in aqueous solution, water reacts with unpredictable results
hydrogen or metal (least reactive) formed at cathode, O2 or halides (if present) at annode
extraction of alluminium
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more reactive than carbon, electrolysis must be used
mixed with cryolite, melted at 850 degrees
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alluminium at cathode, oxygen at annode
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oxygen reacts with annode (CO2), replaced regularly
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strong + weak acids
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in aqueous solution, HCl ionises completely - hydrogen + chloride ions
if ionise completely, strong
pH 1 = 0.1 mol/dm3 H+ ions, decreases ny factor of 10
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changes at electrodes
+ve ion gains electrons, neutral
-ve ion loses electrons, neutral
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