cháu nhớ từ cấp 2 cấp 3 đã học về tính chất của đồng và nhôm rồi. K hiểu các cụ quên hay chém ẩu nữa
nước xi măng của cụ nó là hóa chất chứ có phải hơi nước bt nữa đâu mà chả đổi màu ạ.
(Cement is manufactured through a closely controlled chemical combination of
calcium, silicon, aluminum, iron and other ingredients)
STATUE OF LIBERTY: CHANGING COLORS
The Statue of Liberty is a landmark every American recognizes. The Statue of Liberty is easily identified by its height, stance, and unique blue-green color (Figure 1). When this statue was first delivered from France, its appearance was not green. It was brown, the color of its copper “skin.” So how did the Statue of Liberty change colors? The change in appearance was a direct result of corrosion. The copper that is the primary component of the statue slowly underwent oxidation from the air. The oxidation-reduction reactions of copper metal in the environment occur in several steps. Copper metal is oxidized to copper(I) oxide (Cu2O), which is red, and then to copper(II) oxide, which is black.
2Cu(
s) + \displaystyle \frac{1}{2}21O2(
g) ⟶ Cu2O(
s) (red)
Cu2O(
s) + \displaystyle \frac{1}{2}21O2(
g) ⟶ 2CuO(
s) (black)
Coal, which was often high in sulfur, was burned extensively in the early part of the last century. As a result, sulfur trioxide, carbon dioxide, and water all reacted with the CuO
2CuO(
s) + CO2(
g) + H2O(
l) ⟶ Cu2CO3(OH)2(
s) (green)
3CuO(
s) + 2CO2(
g) + H2O(
l) ⟶ Cu2(CO3)2(OH)2(
s) (blue)
4CuO(
s) + SO3(
g) + 3H2O(
l) ⟶ Cu4SO4(OH)6(
s) (green)
These three compounds are responsible for the characteristic blue-green patina seen today.
Fortunately, formation of the patina created a protective layer on the surface, preventing further corrosion of the copper skin. The formation of the protective layer is a form of passivation, which is discussed further in a later chapter.
courses.lumenlearning.com
Corrosion resistance
Corrosion is the unwanted breakdown and weakening of a material due to chemical reactions.
Copper generally resists corrosion from moisture, humidity, industrial pollution, and other atmospheric influences. However, any corrosion oxides, chlorides, and sulfides that do form on copper are somewhat conductive.
en.wikipedia.org