During World War II, the U.S. Mint switched to zinc-coated steel pennies to conserve copper for military use. However, a small number of 1943 pennies were mistakenly struck in copper ...

Pennies were briefly made of simple steel in 1943 to maintain a solid inventory of copper for the fight against Germany, ...

A copper penny is heated and suspended above the surface of acetone in a beaker. The copper demonstrates heterogenous catalysis in the combustion of acetone to carbon dioxide and water. This exotherm ...