Blue on battery posts; what causes it?

[Arizona_928]

The coin will corrode first, then you just chuck it and get a new one.

[vash]

Anyone answer the question yet?


Sent via Jedi mind trick.

[flatbutt]

Originally Posted by arcsine

From Wikipedia
"Sometimes, it also happens that copper clamps or ringed copper terminals which are used to connect battery with wires corrode. Copper itself is not reactive even if dilute sulphuric acid is poured on it. But when electricity passes, it reacts with sulphuric acid and produce copper sulphate ( CuSO4 ) along with water and sulphur dioxide gas. The equation of this chemical reaction is following:

Cu (s) + 2 H2SO4 (ℓ) → CuSO4 (aq) + 2 H2O (ℓ) + SO2 (g)"

Wow you even balanced it! In answer to the original question the CuSO4 is the blue stuff left behind when the water evaporates.