Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Metal displacement reactions
International Hazard

Posts: 1018
Registered: 7-5-2010
Location: In ur closet
Member Is Offline

Mood: Energetic

[*] posted on 3-12-2012 at 06:45
Metal displacement reactions

what i have never understood is if these reactions are actually useful for metal precipitation

For example, if I want to precipitate copper from CuSO4 with an iron nail, is the iron nail going to get plated and passivated with copper and just stop the reaction, or is the copper going to fall off the iron and dissolve the nail completely?
View user's profile View All Posts By User
International Hazard

Posts: 1806
Registered: 24-10-2010
Location: Flerovium
Member Is Offline

Mood: No Mood

[*] posted on 3-12-2012 at 07:54

It depends on the metals you are using. In most cases I don't believe plating happens - that usually requires some pretty careful setup to get a nice metal plate. I think in your example copper coats the nail in a rough coating that continues to grow into a spongy-looking mass if left in the solution (at least, that's been my experience). Precipitating silver from silver nitrate with copper wire (the classic silver tree demo) results in very pure silver that falls right off the wire when lightly tapped.
View user's profile Visit user's homepage View All Posts By User
Hazard to Others

Posts: 210
Registered: 28-9-2012
Member Is Offline

Mood: No Mood

[*] posted on 3-12-2012 at 08:05

you can ensure complete dissolution of the iron by making it the anode (+) of an electrolytic cell (keep the voltage as low as you can). pure copper will then 'plate' out (most likely in a spongy form, unless other measures are taken) at the cathode (pure copper, such as electrical wire, is preferred as the cathode). once oxidized, the iron will remain in solution. once hydrogen starts bubbling at the cathode, most of the copper ions have been reduced. as the hydrogen ions get reduced, the electrolyte will becomes more basic, so watch out for the formation of insoluble basic iron compounds (add some dilute sulfuric acid before you start, or wash the copper precipitate with it).
View user's profile View All Posts By User
Hazard to Self

Posts: 76
Registered: 2-9-2012
Member Is Offline

Mood: absorbing CO2

[*] posted on 4-12-2012 at 16:23

COat it with zinc -> copper -> silver, chrome, nickel in this sequence if you want to get anything coated.
If you have problems with the first coating, you'll have problems with all the others too x) hehe
View user's profile View All Posts By User

  Go To Top