Food cans are coated with tin but not with zinc because—

Food cans are coated with tin rather than zinc primarily because zinc is more reactive than tin. In the reactivity series, zinc is a more active metal that can undergo oxidation reactions more readily than tin. While zinc is used in galvanization to protect steel through sacrificial protection—where it corrodes preferentially to the underlying iron—this high reactivity makes it unsuitable for food contact [1]. Zinc can react with the organic acids naturally present in many food items, potentially dissolving into the food and leading to toxicity or contamination. In contrast, tin is relatively stable, less reactive than iron, and provides a safe physical barrier that prevents the steel from reacting with air or moisture without leaching harmful substances into the food. Therefore, tin's lower reactivity and chemical stability make it the preferred choice for food packaging.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.5.1 Prevention of Corrosion > p. 54