Re: what is the purpose of pouring coke on corroded battery terminals?

Hi David.

Coke is slightly acidic (as opposed to basic) so it does not dilute battery acid (H₂SO₄), which is quite acidic. Coke will remove corrosion on battery terminals, but water mixed with baking soda (CaCO₃) works just as well if not better. Baking soda and water is slightly basic which appears to react with the corrosion on battery terminals and remove it.

A good book on inorganic chemistry should provide more information on the exact chemical reactions of metals, acids, and bases.