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Q. Why is the Statue of Liberty green? I know that she is made of copper and the rain contains acid. Can you help me with more detail for my science project?

Randal [last name deleted for privacy by Editor]
- Saline, Michigan

"Naked Eggs and Flying Potatoes: Unforgettable Experiments that Make Science Fun"
by Steve Spangler
from Abe Books
info on Amazon


A. Hi, Randal. It's green because the copper has corroded, and the simple salts of copper that have formed are blue-green. Please tell us what your science project is and what grade are you in so we can try to help further.

Acid rain is a phenomenon which can adversely affect aquatic life in high mountain lakes that lack buffering from dissolved salts. But it is a very mild "acid" which probably has little to do with the greening of the statue.

Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

P.S. May 2010: Newer info suggests that acid rain may have a stronger effect on copper than I thought. See reference cited by M Frank on 5/4/10


A. It is green because when it rains the rain makes the copper fade away and that is what is underneath the copper!

Jordyn M [last name deleted for privacy by Editor]
- Philipsburg, Pennsylvania


Jordyn is incorrect. Don't know if he's pulling a prank or just didn't know. Copper is copper colored (the color of a bright new penny), but it tarnishes into copper oxides and salts which are not the same color as copper. The color it tarnishes depends on the conditions it is exposed to. In normal outdoor exposure, with no handling, the blue-green color is typical.

Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

Liberty Costume-Adult

Statue of Liberty Wall Graphic


A. The statue is green 'cause of chemical weathering. Chemical weathering is dependent on available surface for reaction temperature and presence of chemically active fluid. Which that fluid makes the copper green.

Tabitha L [last name deleted for privacy by Editor]
- Michigan


A. The greenish color is a result of the sulfuric acid in the rain reacting with the copper to form copper (II) sulfide.

Jay Carlson
- Lincoln, Nebraska



Put a DARK penny in a vinegar and table salt solution.
Then... leave it in the solution over night
It turns green!

Salt (sodium chloride) combines with acetic acid from the vinegar to produce sodium acetate and hydrogen chloride. Hydrogen chloride (a strong acid) in combination with sodium acetate rapidly cleans the surface of the penny. The cleaning process leaves a very pure metal surface. The surface will corrode when exposed to the water, oxygen, and carbon dioxide from the air. The pennies will turn green when left in the solution over long periods because the copper combines with the acetate in the vinegar.

David Woods
- Red Lodge, Montana


A. The Statue of Liberty is green because of acid rain and the salt water because if you put it in a cup of water with salt and vinegar it will start to make acid.

Malcom E [last name deleted for privacy by Editor]
- Mt.Vernon, New York

Ken Burns's America: The Statue of Liberty

Statue of Liberty Encyclopedia
from Abe Books


2007 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hey,

Why does a copper roof turn green? I'm doing a science project for my grade 10 science class. I've checked everywhere and none of the search engines on the internet can help me so I've put my faith in really people. I would really appreciate it if someone could help and soon as there is a deadline on this project lol. thanks so much your a lifesaver

Rebecca S [last name deleted for privacy by Editor]
school - Ottawa, Ontario, Canada


A. It's pretty simple. The process is called corrosion. Basic copper carbonate is green. Usually, we see copper oxide, but then, CuCO3 is the most basic form. The roofs react with the atmosphere {like the moisture, oxygen, etc}, and hence, the roof gradually gets corroded, and it appears green.

Nanditha J [last name deleted for privacy by Editor]
- Delhi, New Delhi, India


A. It is Green because of the acid that rain produces it also causes the statue of liberty to weather it and chemicals from the rain could cause it to turn a green.

Gillian G [last name deleted for privacy by Editor]
- Eatonton, Georgia


Q. I need help. this is for a science paper and I have no idea what it is.
someone please tell me...

I need help describing the chemical reaction that makes the statue of liberty green.

Megan J [last name deleted for privacy by Editor]
student - Daphne, Alabama


Q. I NEED AN ACCURATE ANSWER! QUICK why is lady liberty green? please make ACCURATE! anna h. PA

ANNA H [last name deleted for privacy by Editor]
- Harrisburg Pennsylvania


The statue of liberty is green because so many people have urinated on it throughout the years. This has caused it to rust which is green. And none of the workers are brave enough to clean 50 year old pee.eewww:)jking! idk!

Katelyn [last name deleted for privacy by Editor]
- Palm City, Florida


Q. Hey;;
can any of you guys tell me how does acid rain effect the Statue of Liberty..and if so how is it restored?&& what is the cost of the restoration
can you tell me please
I need it for my science essay

Katherine [last name deleted for privacy by Editor]
student - Coney Island, New York

January 1, 2008

Q. I need help big time! I also have a science project due tomorrow! I found some information on this website! A BIG THANKS TO ALL OF You WHO WROTE ON THIS PAGE!

Jingie S [last name deleted for privacy by Editor]
- Brooklyn, New York,

March 9, 2008

A. The lady of liberty is green because when copper reacts with oxygen, it turns green.In the oxidation-reduction reaction, copper atoms lose electrons and forms either copper sulfate or copper chloride. Dah! I'm only 12

Kelley S [last name deleted for privacy by Editor]
- New York, New York

March 25, 2008

Q. Hi my name is Hannah and I'm in the third grade,when I asked the question "Why is The Statue of Liberty green?" you gave me a lot of predictions but you didn't tell me which one is right.

Hannah W [last name deleted for privacy by Editor]
- W. Paducah, Kentucky

March 27, 2008

A. Most of the opinions were basically right, Hannah. Whether we call it corrosion or oxidation, it's the same thing. The copper reacted with the air and produced copper salts, which some people called corrosion products or tarnish. When copper is exposed to the air for long periods of time and without anyone handling it like this, that's what happens. And the color of the salts or corrosion products is green. Good luck.

Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

May 7, 2008

Q. What are some effects of acid rain on the statue of liberty I have a science project due in a day and I need some help I am a freshman in high school and have no clue what I am doing

Natashia F [last name deleted for privacy by Editor]
student - Tea, South Dakota

May 7, 2008

A. Hi, Natashia. If your project is due in a day, unfortunately you started too late. I'd ask the teacher for a one-week extension. You really shouldn't proceed on your project without getting to the library.

You need to start with a hypothesis. I would start with "Acid rain is not responsible for the deterioration of the Statue of Liberty", but your hypothesis can, of course, be the opposite. Then you need to accumulate facts about the historical corrosion of the statue and compare it to the historical rise of acidity in the air. If you cannot make a correlation, my hypothesis is almost surely the correct one, and the project is done. If you can make such a correlation, then you're not done yet because you have to explain away all other possible factors -- that's why my hypothesis is much easier to prove (If it's true, of course. You won't be able to prove it if it's not true). I'm sure a huge amount of research went into studying the corrosion before the big repair of 1986, and I'm confident that some popular books at your library will cover the highlights of that.

After you have your hypothesis, you probably want to run an experiment that helps to demonstrate the truth or incorrectness of your hypothesis. Good luck.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

sidebar June 2, 2008

the statue of liberty is BLUE not GREEN.....GOD!


June 2, 2008

Hi, Trever. I'm a very blue-leaning guy. I'll often say things are blue that my wife says are "obviously green". But even to a blue guy like me, the statue is green, not blue. You must be a blue extremist! A blue radical!!

Down with blue fascism!!!  :-)


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

April 15, 2009

Y'all are CrAzY! The Statue of Liberty is neither green and DEFINITELY NOT's teal :D

Patrick C [last name deleted for privacy by Editor]
- New York, New York

My favorite TV commercial --

Kindergarden teacher, pointing to her blouse: Now class, what color is my blouse?
Kids (in unison): GREEN!
Teacher, pointing to her skirt: And what color is my skirt?
Kids (in unison): RED!
Teacher, pointing to her teeth: And what color are my teeth?
Kids (individually): Beige? Uhh . . tan? Ecru?
Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

April 15, 2009


CLARE W [last name deleted for privacy by Editor]

thumbs up signBut what answer are you seeking which is not already on this page, Clare?


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

May 14, 2009

A. Green color is a patina from copper made of Copper carbonate and copper hydroxide. Check this for further detail:

Fyfi Fendir
- Tallahassee, Florida

November 16, 2009

A. Think of a penny. Pennies are copper. If you put water in acid they would turn from red-brown to green. That's all I really know.

Dezerae C [last name deleted for privacy by Editor]
- Holiday Florida

December 1, 2009

Stumbled upon this while looking to explain to my fifth-grader "geologists" exactly what acid rain is and how it happens ... Love the exchange about the color of the statue of liberty and the story about the teacher & the color of her teeth! :)

mary b [last name deleted for privacy by Editor]
student intern - frederick Maryland

January 2, 2010

A. Everyone! The statue of liberty is not green because of acid rain. It is mostly because of the salt in the air from the water. It is called oxidation which means the air makes the metal chemically react, making it look green.

Daisy Barry
- Levittown, New York

sidebar February 19, 2010

thumbsdownI am very disappointed in reading that most of these students on here are waiting until the last minute to do their work and then expect others to give them the easy way out.

D. Galaviz
teacher - New Mexico

February 19, 2010

I understand, D. Maybe teachers can demand writeups from books as references? To me, the biggest problem with the Internet is that students can find answers to their questions without even vaguely understanding the question. To find an answer in books, you need to understand the question.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

April 15, 2010

A. The Statue of Liberty is green/verdigris because it's original copper skin has undergone a process known as patination, due to chemical reactions between metal and water. Copper atoms from the statue mix with the carbon, hydrogen, oxygen,which creates hydroxycarbonate...oxidized copper which turns green.

Martha Cupid-Ansolia
- Petit Valley, Port of Spain, Trinidad

sidebar May 4, 2010

Hey Ted and D,

I am more worried about students looking for easy answers online and getting wrong information, then spreading it around like truth. Especially those that seem reasonable if you don't know anything about the subject, such as those claiming that acid causes oxidation. Chemical reactions are important basics of chemistry that students need to understand. Also, it should be noted that "acid rain", namely carbonic acid and nitric acid speeds up the process of oxidation in copper (

M Frank
- Greenfield, Massachusetts

May 4, 2010

Hi, M.,
Learning is not just accumulating rote facts; students profit even more from seeing multiple viewpoints and learning how to judge their usefulness, limitations, and probable validity. For example, I hereby persist with "Acid does cause oxidation!"

The meaning of "oxidation" isn't restricted to meaning "combine with oxygen"; it means "raise the oxidation state". In the following equation of a simple mineral acid reacting with iron, the oxidation state of the iron has been raised from zero to +2 by the action of the acid:

2H+Cl- + Fe0 => H02^ + Fe+2Cl-2

The iron has been oxidized to an ion with +2 oxidation state.

Thanks for the great reference on acid rain! Now students can carefully consider your opinions and mine if they wish to, and determine for themselves what they think. I bet that most will find you right and me wrong about acid rain, but you wrong and me right about acids causing oxidation.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

July 16, 2010

ted mooney, you are very helpful. thank you.

ashley k [last name deleted for privacy by Editor]
- ladera ranch, California, us

July 20, 2010

Thanks, Ashley. We posted your letter to remind cynical readers (a group which sometimes includes me) that kids often do take the time to say thanks.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

May 10, 2010

Q. Does anyone know the chemical equation for the oxidization of the Statue of Liberty? Are there any problems with this change of color, like environmentally?

Valerie K [last name deleted for privacy by Editor]
school - Chicago, Illinois

September 6, 2010

A. Actually it is green cuz they painted it green

Tenika C. [last name deleted for privacy by Editor]
- Nottingham, England

October 2010

Hi, Tenika. Please point to a reputable reference because I don't think that's accurate.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

October 14, 2010

Q. What year did she turn green? I wish we could see her copper but she is pretty!

kelly r [last name deleted for privacy by Editor]
just wanting to know - austin, Texas

October 26, 2010

A. The statue didn't one day go from copper to green. It's a slow process over many weeks and months. Although, I admit, that would be pretty interesting (and hilarious) to witness.

"And if you will look on your left, you will see the Sta-OH MY GOD! THE STATUE TURNED GREEN!"

Caleb Kim
- Tujunga, California USA

May 21, 2011

Native copper Cu Red
Cuprite Cu2O Red
Chalcocite Cu2O Dark gray
Chalcopyrite FexCuyS Gold Metallic
Covellite CuS Blue
Bornite Cu5FeS4 63.3 Golden brown to copper red
Brochantite Cu4SO4(OH)6 green hydrated copper sulfate
malachite, Cu2CO3(OH)3 green hydrated copper carbonate
azurite Cu3(CO3)2(OH)2 blue hydrated copper carbonate

SLOW Process for change in colours

Meet Patel
- Toronto, Canada

October 13, 2011


IVA M [last name deleted for privacy by Editor]

October 13, 2011

A. Hi, Iva.

The answer isn't real important. What is important is that you learn to synthesize together the various pieces of what you are learning. See if this rings a bell: Did your teacher recently go over the subject of chemical versus physical change? Review that assignment and you'll have your answer. Good luck.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

October 13, 2011

Q. Hi I'm in sixth grade and I'm doing a project about the Statue of Liberty.
I need the specific answer on "Why Is The Statue of Liberty Green".
Please give me the answer A.S.A.P.
(I'm not being rude just so you know)


Natalia K. [last name deleted for privacy by Editor]
student - Staten Island

February 24, 2015

A. It is Green because of the acid that rain produces; it also causes the statue of liberty to weather it, and chemicals from the rain could cause it to turn a green.

Umehani Imran
- Karachi, Sindh, Pakistan

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