[eclecticEel]

Since both copper and nickel have atomic numbers less than iron

Recheck your periodic table. iron is 26, nickel is 28, and copper is 29.

[KarlInOhio]

Recheck your periodic table. iron is 26, nickel is 28, and copper is 29.

Mine's written in crayon from memory. You're right, both nickel and copper are heavier than iron so that reaction should absorb energy rather than create it. Hmm. Well, something interesting is still happening if nickel is being converted to copper.