1Why is it a good idea to sand the surface of a metal if it is not shiny? 2Al is more reactive than zinc and some people think that Al3+ can cause deleterious health effectsWhy might it be a bad idea to cook acidic food in an aluminum pot? would it be better if the pot is shiny and freshly sccrubbed or if the pot has grown dull while being stored for a few weeks? What in the world does metals being shiny not shiny have to do with anything? someone explain :(
1pure metals are shiny unless their surface has oxidised to form the metal oxide on the outside, as in the case of sodiumsanding the surface of a non-shiny piece of metal will make it shiny as sanding will erode away the layer of metal oxide that has formed, leaving the yet-to-be oxidised inner layer of metal exposedthis is the same concept for de-rusting, or removing rust from a piece of iron or steel; when you use products which claim to remove rust from a piece of metal that has rusted, you are in fact removing only the layer of rust on the surface of the metal and exposing the untainted metal underneath 2it's a bad idea to cook acidic food in an aluminium pot as the high temperatures required for the cooking process can and would aid any reaction between the aluminium and the acid in the food, contaminating the cooked food and thus causing the alleged deleterious health effects in the questionit would be better to use a pot that has grown after non-use for a few weeks as pure aluminium on the surfaces of the pot will readily react with the oxygen in the air to form a layer of non-porous aluminium oxide (Al2O3) on the exposed areas of the pota unique property about Al2O3 is that it is impervious to air and will protect the unreacted aluminium beneath it from further reaction with O2Al2O3 is also stable under high temperatures and so will not react with the acidic food during cookingthis way, the food will not be contaminated and be safe for consumption but please, do not sand away the protective layer of Al2O3 before cooking and wash the pot with soap and warm water before use )
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