I know aluminium forms a protective layer of aluminum oxide and hence water does not corrodes it easily.However, since the oxide is amphoteric, won't it react with acids and subsequently be dissolved?What is the main reason aluminium cans are used?
Because of the aluminum chemical properties. Aluminum Oxide (Al2O3) is an extremely hard and compact material, so when the metal is exposed, it gets a very thin coat of Al2O3 that has a 9 hardness (only diamond is harder), that protects the rest of the metal from the atmosphere. Also, you should question if the phosphoric acid actually attacks aluminum, that is because that acid is found in Pepsi and coke..., BUT, as far as i know cans have a little plastic coat inside..., so the liquid does not get in touch with the aluminum.
because they are light and easy to smash with your hand
The old tin ones and bottles hurt when you smash them on your forehead
