Why Are Food Cans Coated With Tin Rather Than Zinc?
Food cans are coated with tin and not with zinc. Why?
Why Are Food Cans Coated With Tin Rather Than Zinc
Tin is less reactive than zinc. It is less likely to dissolve in the liquid stored in the food cans. Tin reacts only with powerful acids, whereas zinc can easily react even with tomatoes, so it is not safe to store food in zinc-plated cans.
– Written By Pratibha Upadhyay
Food items are packed in metal cans to preserve their content for a longer period. While doing the same, we generally come across food cans manufactured with tin coating and not zinc, this is due to a specific scientific reason, that is, REACTIVITY. We all are aware of the electrochemical series, which determines the reactivity sequence of metals, where Zinc is in the seventh position, depicting its high reactivity. Thus, it can react with the slightest acid and make the edible content of the can poisonous. Instead of preserving the food, it will cause further degradation due to chemical reactions caused by the highly reactive zinc. On the other hand, we have Tin, which, as compared to zinc, lies behind in the reactivity series of the metals and is less reactive and thus will not be reacting with the edible content and will even keep it fresh and hygienic without causing any kind of chemical reaction. REACTIVITY is the primary reason for using tin-coated cans for storing food and not zinc-coated ones.
A secondary reason supporting the previous fact is that Tin has a greater boiling point, that is 2,602 °C, whereas Zinc has a mere boiling point of 907°C.
Due to the above-mentioned factor, tin, being a much costlier metal than zinc, is used to coat food cans; otherwise, the primary objective of preserving the food item will not be solved, and we all shall be consuming harmful poisonous substances in the name of canned food.
– Written By Anushree Ray
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