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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: chemistrie on April 25, 2005, 05:03:51 AM

Title: remove aluminium oxide layer
Post by: chemistrie on April 25, 2005, 05:03:51 AM

What is the chemical equation of aluminium oxide reacts with mercury(II)chloride?

Title: Re:remove aluminium oxide layer
Post by: Borek on April 25, 2005, 06:10:25 AM

IIRC mercury doesn't remove oxide layer. When I was a student (eons ago) there were aluminum coins used in Poland. Mercury put on the coin did not generated any effect. You have to squeeze some mercury between two coins and rub them (removing oxide layer mechanically) to start the reaction.

Title: Re:remove aluminium oxide layer
Post by: jdurg on April 25, 2005, 01:32:53 PM

Mercury does remove the oxide layer off of aluminum metal.  Take a look at one of the more recent issues of Popular Science magazine.  They have a good demonstration there of what happens when elemental mercury contacts aluminum metal.  It's pretty dramatic.

Title: Re:remove aluminium oxide layer
Post by: Borek on April 25, 2005, 06:15:20 PM

Perhaps the problem lies in the fact that coins were made from some alloy that have slightly different properties.

I can only witness what I have seen - our coins didn't show signs of any reaction before rubbing, but after rubbing the reaction was quite interesting and visible - but didn't last long, as the mercury was taken away by the groving layer of aluminum oxide so we have never seen more than a few milimiters thick grey mass being mixture of oxide and mercury.

Perhaps additional problem was grease on the surface? We have never tried degreased coins, they were just taken from our (rather shallow :) ) pockets.

Title: Re:remove aluminium oxide layer
Post by: xiankai on April 26, 2005, 07:41:59 AM

i thought it was supposed to be mecuric (II) chloride? does mecury work fine too?