What is green copper?

  1. ShawnD

    ShawnD 953
    Science Advisor

    Pure copper metal is orange (or pink after being anodized), copper hydroxide is blue, copper oxide is black. So then why is the statue of liberty green?
  2. jcsd
  3. Pengwuino

    Pengwuino 6,942
    Gold Member

    Supposedly its oxidation... and ive seen copper turn green though too..
  4. Math Is Hard

    Math Is Hard 4,635
    Staff Emeritus
    Science Advisor
    Gold Member

    I've seen lots of old pennies turn green. Must be the same thing.
  5. chroot

    chroot 10,351
    Staff Emeritus
    Science Advisor
    Gold Member

    I'm no chemist, but I believe there are several different oxidation states of copper, one of which is green.

    - Warren
  6. My guess was copper sulfate, but I looked it up and its probably more likely copper carbonate. As you may have learned in your intro chem classes(especially if your teacher was an environmental guy like mine) water reacts with carbon dioxide to form carbonic acid, which gives all rain its slight acidity. This carbonic acid will then react with the copper to form cupirc and cuprous carbonate.
  7. sulfates and acetates will turn it green.
  8. Borek

    Staff: Mentor

    Last edited by a moderator: Aug 13, 2013
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