This is a great demonstration to show the reactivity of aluminium. Both a displacement reaction and a reaction with acid.
Aluminium foil is added to a mixture of copper II chloride solution and concentrated hydrochloric acid, in a large conical flask. The acid removes the oxide coating on the aluminium allowing it to displace the copper, it will also react with the acid to produce hydrogen.
After about 30 seconds enough hydrogen is being produced that it is possible to ignite it. The characteristic ‘pop’ opf hydrogen is accompanied by a green flame, due to the copper.
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