[paul.fr]

I have this cup full of lemon juice, and everytime i put a strip of aluminium in to it, bubbles form! What are these bubbles and why are they being produced?

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I have this cup full of lemon juice, and everytime i put a strip of aluminium in to it, bubbles form! What are these bubbles and why are they being produced?

2Al + 2H₃Citr → 2AlCitr + 3H₂

where H₃Citr means citric acid and AlCitr means aluminum citrate. The hydrogen gas H₂ is responsible of the bubbles.

Anyway AlCitr idrolizes in water forming Al₂(OH)₃ and H₃Citr again.