Science on the Road: Visiting the Statue of Liberty & Chemical Reactions

In September, we spent a few days in New York City on the island of Manhattan, the city’s historical birthplace and the economic and center. The borough contains several smaller islands including Liberty Island, Ellis Island (shared with New Jersey), Governors Island, and a few others. We were really looking forward to exploring the area and learning more about the history of the area, specifically the Statue of Liberty.

Science of the Statue of Liberty @EvaVarga.netWe arrived in Manhattan via Amtrak train from Boston in the early afternoon. We thereby opted to take in the Statue of Liberty and Ellis Island the following day when we could arrive early and board the first cruise boat. This turned out to be a wise decision as the queue upon our return to the main island was very long.

We grabbed a quick bite at the deli just outside the Courtyard Marriott on 40th where we are staying then hopped the green line express to Bowling Green. Here, we walked the short distance to the boarding area.

We immediately made our way to the National Park Visitor Center after we disembarked. Here we stamped our Park Passport Books and inquired about guided tours. We were in luck in that the first tour would begin in just 20 minutes. We took a few candid photos (Geneva pulled out her sketch book) as we waited.

As we planned to spend all our time in this area, we opted to purchase the New York CityPASS as the majority of the attractions were in this general area. In addition to Statue of Liberty and Ellis Island cruise, the pass provided us with tickets to each of the following attractions:

  • Statue of Liberty & Ellis Island
  • The Empire State Building
  • American Museum of Natural History
  • The Metropolitan Museum of Art
  • Guggenheim Museum 
  • 9/11 Memorial & Museum   

 

Science & Art of Liberty Island and the Statue of Liberty @EvaVarga.netVisiting the Statue of Liberty & Liberty Island

Liberty Island Tour

The group that gathered for the guided tour of Liberty Island was small and thereby very intimate. I am surprised more people don’t take advantage of this opportunity – they are so very informative and best of all, FREE!

As we listened to the park ranger, we learned the idea of gifting the United States with a monument was first proposed in 1865 by Frenchman Edouard de Laboulaye. Sculptor Frederic Auguste Bartholdi was commissioned to design a sculpture ten years later, with a goal of completing the work in 1876 to commemorate the centennial of the American Declaration of Independence.

As a joint venture between the two nations, it was agreed that the American people were to build the pedestal (carved in granite, the pedestal was designed by architect Richard Morris Hunt in 1884), and the French people were responsible for the Statue and its assembly here in the United States.

In France, public fees, various forms of entertainment, and a lottery were among the methods used to raise funds for the project. In the United States, theatrical events, art exhibitions, auctions and prizefights assisted in financing the construction.

Poet Emma Lazarus wrote her famous sonnet “The New Colossus” in 1883 for the art and literary auction to raise funds for the Statue’s pedestal.

Not like the brazen giant of Greek fame,
With conquering limbs astride from land to land;
Here at our sea-washed, sunset gates shall stand
A mighty woman with a torch, whose flame
Is the imprisoned lightning, and her name
Mother of Exiles. From her beacon-hand
Glows world-wide welcome; her mild eyes command
The air-bridged harbor that twin cities frame.
“Keep, ancient lands, your storied pomp!” cries she
With silent lips. “Give me your tired, your poor,
Your huddled masses yearning to breathe free,
The wretched refuse of your teeming shore.
Send these, the homeless, tempest-tost to me,
I lift my lamp beside the golden door!”
 – Emma Lazarus

Science & History of the Statue of Liberty @EvaVarga.netCentennial Gift 10 Years Late

Financing for the pedestal was completed in August 1885, and pedestal construction was finished in April 1886. The Statue was completed in France in July 1884 and arrived in New York Harbor in June 1885 onboard the French frigate “Isere.”

In transit, the Statue was reduced to 350 individual pieces and packed in 214 crates. The Statue was reassembled on her new pedestal in four months’ time. On October 28, 1886, President Grover Cleveland oversaw the dedication of the Statue of Liberty in front of thousands of spectators.

Homage to the Statue of Liberty Supporters

On Liberty Island, there are several small sculptures commemorating several of the key supporters of the Statue of Liberty gift. I really enjoyed hearing the personal triumphs that made it all possible.

  • Edouard de Laboulaye ~ The “Father of the Statue of Liberty.” He provided the idea that would become the Statue.
  • Frederic Auguste Bartholdi ~ The French artist and sculptor who designed the Statue of Liberty Enlightening the World.
  • Alexandre-Gustave Eiffel ~ The architect and engineer who designed the Statue’s internal support.
  • Emma Lazarus ~ The poetess who wrote “The New Colossus” to help raise money for the pedestal’s construction.
  • Joseph Pulitzer ~ The newspaper publisher who helped raise the money needed to complete the pedestal’s construction.

One of the things I overheard many of the young visitors ask as we walked about the island was, “Why is it green?” I knew that when I returned home, this was a concept I wanted to revisit with my children.

Bring it Home ~ Oxidation Reduction Reactions

Why is the Statue of Liberty Blue-Green?

Begin by showing students photographs of the Statue of Liberty.  Ask students to describe the color. Students usually give the right answer: that it is blue or aquamarine (blue-green). Now ask them why it is this color. Students generally have no clue.

Explain that the color is due to the oxidation of copper. Next, show them a piece of rusted metal and point out that the red color of rust is caused by the oxidation of iron.

Science of Oxidation and the Statue of Liberty @EvaVarga.netOxidation Explained with Chemical Equations

Chemical reactions can be divided into two classes: redox (reduction-oxidation) reactions and non-redox reactions based on whether electron transfer process is involved or not. A redox reaction consists of two half reactions: a reductive half in which a reactant accepts electrons and an oxidative half in which a reactant donates electrons.

2Cu + O2 → Cu2O

The nature of a redox reaction is that one reactant donates its electrons to the other reagent. For example, in the oxidation of copper by oxygen, copper atoms donate electrons to an oxygen molecule so copper is oxidized while oxygen is reduced.

The Statue of Liberty gets its blue-green color from patina formed on its copper surface mainly through oxidation along with several other chemical reactions. The main constituent of patina contains a mixture of 3 compounds: Cu4SO4(OH)6 in green; Cu2CO3(OH)2 in green; and Cu3(CO3)2(OH)2 in blue. The following reactions are involved.

2Cu2O + O2 → 4CuO

Cu + S → 4CuS 

The oxidation starts with the formation of copper oxide (Cu2O), which is red or pink in color (equation 1), when copper atoms initially react with oxygen molecules in the air. Copper oxide is further oxidized to copper oxide (CuO), which is black in color (equation 2). In the 19th and early 20th century, coal was the major fuel source for American industry and it usually contains sulfur. Thus, the black copper sulfide (CuS) also forms (equation 3).

2CuO + CO2 + H2O → Cu2CO3(OH)2

3CuO + 2CO2 + H2O → Cu3(CO3)2(OH)2

4CuO + SO3 +3H2O → Cu4SO4(OH)6

Over the years, CuO and CuS slowly reacts with carbon dioxide (CO2) and hydroxide ions (OH-) in water from the air to eventually form Cu2CO3(OH)2 (equation 4) , Cu3(CO3)2(OH)2 (equation 5) and Cu4SO4(OH)6 (equation 6), which constitute the patina. The extent of humidity and the level of sulfur-related air pollution have a significant impact on how fast the patina develops, as well as the relative ratio of the three components.

Take it Further

Can you think of another oxidation reduction reaction? Write out the chemical equations to further describe this process.