Question

What is the chemical equation for why the Statue of Liberty turned green

Answer 1

The formula is as follows

2Cu + O2 ---> 2CuO

When two copper atoms react with a diatonic oxygen, they form copper oxide (rust)

Answer 2

The reason copper coins dull in the first place, is because copper reacts with oxygen in the air and form a layer of copper oxide which is a dull greenish-grey colour. When you mix the salt (sodium chloride) with the vinegar (acetic acid) you form Sodium acetate and Hydrogen chloride.