Oxidation and corrosion tarnish pennies
oxygen
Yes copper tarnishes !
pennies don't rust, they're made of cooper, rust is iron-oxide (meaning it has iron and oxygen in it). But copper oxidises (tarnishes). so a liquid with a high oxygen content would work
Silver is commonly used to make jewelry and tarnishes over time due to exposure to air and humidity.
Chemical change
Chemical change
Chemical change
It tarnishes a ten yo boy
copper
the bank!
Pure tin is shiny but it quickly tarnishes and dulls.
Oxygen