Sciencemadness Discussion Board

An experiment on holmium corrosion

Brain&Force - 9-6-2015 at 18:11

I've found that holmium metal appears to be really corrosion resistant in the dry San Diego air. 6 months of handling has led to basically no change to the surface of any of the pieces I have. This is in strong contrast with other rare earth metals like samarium and lanthanum. I'm going to be looking at how fast the less reactive rare earth, holmium, reacts with water.

For this experiment 5 pieces of holmium (4 small bits and 1 large one, totaling a few tenths of a gram) will be added to ordinary tap water. I'll monitor it and post photos and updates as the metal reacts and things start to happen.

blogfast25 - 9-6-2015 at 18:15

Very obvious question (that I could verify myself but I'm lazy like that!): does this result in any way correlate with oxidation potentials or enthalpies of formation (oxide)?

j_sum1 - 9-6-2015 at 18:42

You are probably aware of this, but I will post it anyway.
http://www.elementsales.com/re_exp/

One of the simplest and most graphic studies done IMO.

Brain&Force - 9-6-2015 at 18:54

Quote: Originally posted by blogfast25  
Very obvious question (that I could verify myself but I'm lazy like that!): does this result in any way correlate with oxidation potentials or enthalpies of formation (oxide)?


Not that I'd know of. Especially considering the weirdness of some lanthanides (europium) when oxidizing (going to the +2 vs +3 state).
Quote: Originally posted by j_sum1  
You are probably aware of this, but I will post it anyway.
http://www.elementsales.com/re_exp/

One of the simplest and most graphic studies done IMO.


Yeah, I'm just doing the same experiment, but with the metal under water.

AJKOER - 9-6-2015 at 21:26

If you want to speed part of the experiment up, use one piece of metal, add a touch of sea salt to some dilute H2O2 and tap water.

Then heat in a microwave for 30 seconds and see if there is any evidence of a self-sustaining reaction.

MrHomeScientist - 10-6-2015 at 05:49

Toss some bleach in there while you're at it!

Brain&Force - 10-6-2015 at 10:55

<a href="http://imgur.com/n9Vk4oW"><img src="http://i.imgur.com/n9Vk4oW.jpg" width=800 /></a>

The experiment has begun at 11:50 PDT - I will provide updates as needed.

[Edited on 10.6.2015 by Brain&Force]

Molecular Manipulations - 10-6-2015 at 13:36

Quote: Originally posted by AJKOER  
If you want to speed part of the experiment up, use one piece of metal, add a touch of sea salt to some dilute H2O2 and tap water.

Then heat in a microwave for 30 seconds and see if there is any evidence of a self-sustaining reaction.

This is an experiment. He's not just trying to destroy his holmium you see.
Looking forward to seeing your results Brain&Force.
Could you show some other lanthanides reacting at the same time, to gauge relative reaction speeds?

Brain&Force - 10-6-2015 at 14:49

Quote: Originally posted by Molecular Manipulations  
Quote: Originally posted by AJKOER  
If you want to speed part of the experiment up, use one piece of metal, add a touch of sea salt to some dilute H2O2 and tap water.

Then heat in a microwave for 30 seconds and see if there is any evidence of a self-sustaining reaction.

This is an experiment. He's not just trying to destroy his holmium you see.
Looking forward to seeing your results Brain&Force.
Could you show some other lanthanides reacting at the same time, to gauge relative reaction speeds?


I might try samarium here soon. Meanwhile, I ended up dropping the experiment cup and losing two pieces right after I started. Here's everything three hours after the start:

<a href="http://imgur.com/FEUQ96a"><img src="http://i.imgur.com/FEUQ96a.jpg" width=800 /></a>

diddi - 10-6-2015 at 17:45

everyone strives to extract metallic lanthanides from mixtures and salts etc, but Brain&Force seeks to destroy them? All in the name of science :(

blogfast25 - 10-6-2015 at 18:20

Quote: Originally posted by diddi  
everyone strives to extract metallic lanthanides from mixtures and salts etc, but Brain&Force seeks to destroy them? All in the name of science :(


This deserves the title <i>'stoooopidest comment of the week on SM!'</i>. Well done, competition was stiff but you made the grade.

diddi - 10-6-2015 at 18:56

hahah blogfast25. for what its worth, I sold Brain&Force his lanthanides and we often discuss lanthanide chemistry and compare notes. but thanks for the nomination :)

Brain&Force - 10-6-2015 at 22:44

Now we're talking corrosion! The reaction is reminiscent of magnesium added to water. The hydroxide powder appears white without any color changing properties.

<a href="http://imgur.com/VMyjkQm"><img src="http://i.imgur.com/VMyjkQm.jpg" width=800 /></a>

I decided to fish out the holmium from the water and photograph it to see if it had lost its shine - it did, but it wasn't totally black.

<a href="http://imgur.com/8oHq2jW"><img src="http://i.imgur.com/8oHq2jW.jpg" width=800 /></a>

Click for full resolution images.

Molecular Manipulations - 11-6-2015 at 16:01

Cool.
Probably not that relevant, but what's the pH of your tap? What's the pH of the solution after corrosion?
Would you be willing to convert the hydroxide to (III) oxide? I'd like to see the color change that occurs depending on lighting, perhaps post a YT video?
Also the very strong paramagnetic properties of the oxide would be interesting to watch.
You say you dropped some, may I ask if you bothered to pick it up?:D

[Edited on 12-6-2015 by Molecular Manipulations]

Brain&Force - 11-6-2015 at 16:43

I don't have pH indicator strips so I can't give you any information. I dropped everything, these are the pieces I put back.

My plan was initially to make the oxide/hydroxide, so I'm going to be doing stuff with the leftovers.

<a href="http://imgur.com/Y3uOd4X"><img src="http://i.imgur.com/Y3uOd4X.jpg" width=800 /></a>

Molecular Manipulations - 11-6-2015 at 18:42

Haha, my messy lab two years ago - drop anything, you'll never see it again! Know how that is...
Not sure about where you are, but I've found pH strips at dollar stores, school supply stores, hardware stores, and of course the internet. I'm not asking you to buy something just for this, but pH paper (or some way to measure pH) is kind of a necessity in chemistry. And you don't even have to wait for shipping.
Anyway, tap tends to be alkaline, so I'd guess in pure water (or at least neutral water) the reaction would go slightly faster, not that it really matters though.
[EDIT] That latest picture makes holmium look much more reactive than magnesium IMO. I haven't put any Mg in water in a couple years, but from what I remember, a small ribbon 1 centimeter long (not sure about thickness, standard ribbon though) took at least two weeks to fully react, in enough water to dissolve all the hydroxide (which is a lot). It may have been rather cold in the lab though, no idea what season I did it in (10 degrees C colder could make the reaction take twice as long).


Sorry for the off topic ramble (I may or may not be drunk right now:D).
Having never messed around with lanthanides (except some impure neodymium sulfate, from magnets) I'm just trying to add to a topic I know very little about...
Cool experiment though, wish I could get back in the lab, so damn busy, not to mention out of town.
Here I go again... where the hell did I put my bottle...:P

[Edited on 12-6-2015 by Molecular Manipulations]