In Senior Infants we did a science experiement called Copper Caper where we used vinegar and salt to clean dirty copper coins.

We poured a quarter of a cup of vinegar into a plastic tub and added a teaspoon of salt to it, stirring it well until the salt had dissolved.

Next we put our dirty coins into the mixture and straight away we noticed that they were cleaner. After a few minutes we took the coins out and rinsed half of them with water. We left the other half unrinsed on kitchen towel. After a few minutes we noticed that the unrinsed coins were looking dirty again turning a blue-green colour, while the rinsed coins were still shiny and clean.

Next we put some new and shiny nails and a screw into the mixture. After a few minutes the nails were starting to change to a brown colour while the screw had bubbles coming out if it. The screw eventually turned black.

Why did all of this happen? 

Lots of chemical reactions happened during our experiment between the metals in the coins, nails and screw, the salt/vinegar mixture and oxygen from the air.

The salt and vinegar mixture is an which cleaned the dirt off the coins.

The unrinsed coins turned a blue/green colour because the copper in the coins mixed with oxygen from the air and chlorine from the salt.