Chemistry question/Fuming Ammonia/aluminum

9/22/20, 1:53 PM #1

Barry Irby
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Chemistry question/Fuming Ammonia/aluminum

Barry Irby

I have fumed the console I built for my son out of white oak.

I had it sitting on my roll around bench and put some shallow pans under it for the ammonia and then sealed it up in polyethylene. This morning I opened the bag after about 24 hours. Looks good. Went to dispose of the remnants of the ammonia and found it had reacted with the aluminum pans. They were sort of chalky gray and when I washed them they are blackened where in contact with the ammonia. (Cleaning ammonia I got from Walmart, does not list the strength.)

So, what is the chemistry? What effect did this have on the fuming? Should I throw the pans away. (I used and cookie sheet and a pizza pan to get large surface area.)

By the way, I still had to fume the base and drawers, so I repeated what I did hoping to get matching results.

Re: Chemistry question/Fuming Ammonia/aluminum

9/22/20, 5:31 PM #2

JL
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Re: Chemistry question/Fuming Ammonia/aluminum

JL

Basically speaking (pun intended) - you are getting aluminum hydroxide (Al(OH)3) when you expose aluminum pans to ammonia or basic chemicals.

If the pans aren't etched too badly, take a pad and scrub off the whitish coating.

Re: Chemistry question/Fuming Ammonia/aluminum

9/22/20, 6:17 PM #3

Bill Tindall, E.TN.
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Re: Chemistry question/Fuming Ammonia/aluminum

Bill Tindall, E.Tn.

Al + H2O + OH- = Al(OH-)3 + H2 not balanced

aluminum in the presence of hydroxide reduces water to hydrogen plus hydroxide

product is aluminum hydroxide and hydrogen

Re: Chemistry question/Fuming Ammonia/aluminum

9/22/20, 6:32 PM #4

William Duffield
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Re: Chemistry question/Fuming Ammonia/aluminum

William Duffield

I'm not sure the offending reaction was the same as JL and Bill describe (SWMBO is not divulging any secrets), but the result looks the same, so I used my old standby, Bar Keeper's Friend and a ScotchBrite pad, to remove the grey oxide and restore the shine to our cookie sheet.

Re: Chemistry question/Fuming Ammonia/aluminum

9/22/20, 11:09 PM #5

Barry Irby
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So, am I going to die?

Barry Irby

I have long since forgotten most of what I learned in freshman chemistry.

So, It appears that using aluminum "destroyed" or consumed some if not all of the ammonia???? Leaving less available for the reaction in the oak?

One of the pans was steel and appears to be unscathed except it has lost it's nice brown coating (Baked On fond?) Could it be that this one is the one that provided the ammonia that reacted with the wood?

If you think education is expensive you should try ignorance. A thousand ways to die in the west.

Re: Chemistry question/Fuming Ammonia/aluminum

9/22/20, 11:33 PM #6

Dave Bair
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Re: Chemistry question/Fuming Ammonia/aluminum

Dave Bair

I've always used shallow glass baking pans since I had an aluminum store-bought- pie plate disintegrate.

Re: Chemistry question/Fuming Ammonia/aluminum

9/23/20, 12:43 PM #7

Bill Tindall, E.TN.
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Re: So, am I going to die?

Bill Tindall, E.Tn.

So, It appears that using aluminum "destroyed" or consumed some if not all of the ammonia???? Leaving less available for the reaction in the oak?

The reaction is slow if the aluminum surface area is small. And, the reaction uses up water, not ammonia. Do you see any hint of ammonia being used up in the reaction I provided?

If the aluminum is in powder form the reaction is zippy. An example is Draino, a mix of aluminum particles and sodium hydroxide. When water is added it releases hydrogen bubbles and lots of heat.

Chemistry question/Fuming Ammonia/aluminum

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