Oxidation of Copper, Gold and Aluminum

[Michael DLS]

Hello guys...I have a difficulty in determining the factors that greatly affect the rate of oxidation of Copper, Gold and Aluminum.

On the other hand i know that of the three elements, Aluminum has the highest tendency to oxidize,2nd is Copper and third is Gold basing on their Electronegativity.

 

[luben111]

It's not only Electronegativity that affects the rate of oxidation. For example Aluminium is highly reactive element but the Aluminium oxide creates very strong and even layer which prevents the surface from further oxidation.

 

[Raza]

https://www.physics.gatech.edu/files/u26/papers/0310.pdf
**broken link removed**
https://www.ajol.info/index.php/wajae/article/viewFile/45666/29146

A lot of factors involved in each metal and all are, almost, discussed separately. A lot of references come up. Google to explore more.

 

[Michael DLS]

i think that is PATINA?

---------- Post added at 15:41 ---------- Previous post was at 15:39 ----------

It's not only Electronegativity that affects the rate of oxidation. For example Aluminium is highly reactive element but the Aluminium oxide creates very strong and even layer which prevents the surface from further oxidation.

IT is PATINA??

---------- Post added at 15:46 ---------- Previous post was at 15:41 ----------

https://www.physics.gatech.edu/files/u26/papers/0310.pdf
**broken link removed**
https://www.ajol.info/index.php/wajae/article/viewFile/45666/29146

A lot of factors involved in each metal and all are, almost, discussed separately. A lot of references come up. Google to explore more.

Thank you raza..if we talk about temperature..does Copper, Gold and Aluminum has temperature ranges that their rate of oxidation increases significantly?

---------- Post added at 15:50 ---------- Previous post was at 15:46 ----------

https://www.physics.gatech.edu/files/u26/papers/0310.pdf
**broken link removed**
https://www.ajol.info/index.php/wajae/article/viewFile/45666/29146

A lot of factors involved in each metal and all are, almost, discussed separately. A lot of references come up. Google to explore more.

In addition..I have Oxygen as my Oxidizing Agent for Copper,Gold and Aluminum..

 

[jpanhalt]

This article will explains why using only oxygen, gold will not oxidize:

**broken link removed**

You need a more electronegative element than oxygen to react with gold directly, so you move to the right in the periodic table. Fluorine is right next to oxygen, but chlorine is more commonly used. If you look up aqua regia you will find that it dissolves gold not because of the strong acids per se (i.e., nitric and hydrochloric), but because of the high chloride concentration that is contributed by the HCl in the mixuture.

If you will narrow your questions a little to be more specific, I am sure you will get better answers. As for the word "patina", I have rarely heard that applied to aluminum. It is more frequently applied to copper and its alloys, considering only the three metals you mention. Aluminum is also a bit of an oddball in that group of three metals in that it reacts with both acids and bases (i.e., amphoteric).

John

 

[Raza]

In addition..I have Oxygen as my Oxidizing Agent for Copper,Gold and Aluminum..

Do you mean the environment has only Oxygen as the reacting agent and no other gas ?. If it is in open air environment then the Oxygen may will main agent but other gases will be also active. It is not PATINA but the Oxidation.

 

[FvM]

As clarified, the original question is referring to oxidation in the narrow sense. As commonly known Al and Cu are oxidized by "clean" air, gold isn't. Al is a special case, because it's protected by a very stable oxide layer against further oxidation. Some pollutants (most effective is mercury) can destroy this protective layer.

Patina is more a historical technology term than an exact chemical specification. I'm not aware of it's usage for aluminium. It's common for copper and it's alloys, being a mixture of different compounds, oxide, chloride, carbonate etc. You'll find some kind of patina on old gold parts as well, but they are never pure gold. I don't know if it contains a relevant part of gold oxide.

 

[Raza]

PATINA infact (known to many) is defined as usually a Green film formed naturally on Copper and Bronze by long exposure or artificially (by acids) and often valued aesthetically by its color, some times created specially on furniture (wood and metallic) for some artistic view. The PUTTY which used by Vehicle Painters is also derived fro this PATINA (to form a layer under the paint for smooth look). Aluminum has the property that the oxidation gives a very firm layer to protect it, even, to avoid further deeper oxidation. Gold has the most firm stand against oxidation in normal environment.