Turning Green

By Kylie

What if I told you the Stature of Liberty wasn’t originally green??

The outer layer of the statue is coated in a thin layer of copper plates. When it was assembled in 1886, its natural colour reflected this, being copper brown in colour. Over time, the statue has gradually turned a green colour due to a process called oxidation, where the colour change is due to exposure of oxygen and air. The green colour is actually from a layer formed over the top called copper oxide.

Exposure to acid from rain also caused the process to speed up.

 

Here’s a simple experiment you can try at home!

Materials:

      -  Copper pennies (anything made of copper will suffice)
      - White vinegar
       - Paper towel
       - Bowl

 Procedure:

1. Place the pennies on top of the paper towel in the bowl
2. Pour enough vinegar in the bowl for the towel to become saturated
3. Turn the coins regularly and pour more vinegar when towel becomes dry

4. Observe the effects over a couple of days – the longer you leave them, the greener they should become!

The vinegar acts just like the rain did on the statue, speeding up the reaction.

Sources:

http://wonderopolis.org/wonder/why-is-the-statue-of-liberty-green

http://buggyandbuddy.com/science-for-kids-make-a-penny-turn-green/