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Metallic Strontium

uzaymaymunu - 22-6-2015 at 12:45

Is it possible to get metallic strontium for us?
I mean:
A-With downs cell is possible?
B-Can someone explain the industrial method with details (Sr-oxide +Al) ?
C-Is it possible to get metallic Sr with catalyzed magnesium reduction method to get potassium.

Thanks.

elementcollector1 - 22-6-2015 at 17:49

A) Yes. Building an amateur Downs Cell, though, is quite a different matter.
B) Mix stoichiometrically. Set on fire. Collect metal.
C) What? Do you want Sr or K? Explain.

Request this thread to be moved to Beginnings.

Hawkguy - 22-6-2015 at 17:54

Quote: Originally posted by uzaymaymunu

Is it possible to get metallic strontium for us?
I mean:
A-With downs cell is possible?
B-Can someone explain the industrial method with details (Sr-oxide +Al) ?
C-Is it possible to get metallic Sr with catalyzed magnesium reduction method to get potassium.

Thanks.

I am so confused. It doesn't help your case for the catalyzed Magnesium (reduction) method that Strontium has a high melting point.

battoussai114 - 22-6-2015 at 18:23

Quote: Originally posted by elementcollector1

A) Yes. Building an amateur Downs Cell, though, is quite a different matter.
B) Mix stoichiometrically. Set on fire. Collect metal.
C) What? Do you want Sr or K? Explain.

Request this thread to be moved to Beginnings.

C)I think he meant similarly to what is done to get potassium,

violet sin - 22-6-2015 at 19:37

" C-Is it possible to get metallic Sr with catalyzed magnesium reduction method to get potassium. "

I read this as:

C- Is it possible to get metallic Sr with ( a ) catalyzed magnesium reduction(, like that) used to get potassium.

elementcollector1 - 22-6-2015 at 19:49

Oooh. Then, the answer is likely no - even if strontium did form, it'd probably form as a coating on the magnesium. Potassium works well because it melts off.

WGTR - 22-6-2015 at 20:03

My first thought would be a modification of "A". I haven't tried this, so your mileage may vary (YMMV). If anyone thinks I'm overlooking something obvious, jump on in.

Using a KCl-SrCl2 melt...

...electrolyse strontium into a molten copper/strontium cathode. The alloy should be kept concentrated enough in copper that it will stay underneath the electrolyte. Two anodes would be used, one graphite, and the other made from copper. The current would be split between the two anodes to both initiate and maintain the proper alloy in the cathode as more strontium is deposited. Here is the Cu-Sr system:

[3]

Potassium and strontium are immiscible in both solid and liquid states [1]. Potassium and copper are also immiscible in both solid and liquid states [2]. For this reason I don't think potassium would compete favourably with strontium for deposition, which is readily soluble in copper, and forms stable compounds with it [3], at least as long as the strontium concentration doesn't go too high.

After batch electrolysis is accomplished, I think the potential could be reversed in the cell, with the molten cathode becoming the anode. The strontium would be stripped from the anode (with some magnetic stirring of the molten anode probably required), and deposited as a solid at the cathode. I don't know if potassium would co-deposit with it or not at this point, but chlorine would not be produced during this purification step.

1. http://dx.doi.org/10.1007/BF02869237
2. http://dx.doi.org/10.1007/BF02868995
3. http://dx.doi.org/10.1007/BF02872963

blogfast25 - 23-6-2015 at 08:13

Quote: Originally posted by elementcollector1

B) Mix stoichiometrically. Set on fire. Collect metal.

Aluminothermic reduction of SrO with Al? That reduction is not thermodynamically favourable in open crucible conditions.

But in analogy with MgO/Al, Sr preparation by this method but under high vacuum and at high temperature (> 1,000 C) might be possible.

Sr's BP of 1,377 C is strongly lowered in high vacuum but remains higher than Al's.

The equilibrium 3 SrO(s) + 2 Al(l) < === > 3 Sr(g) + Al2O3(s) then shifts to the right because Sr vapour is distilled off.

Not for the faint of heart and certainly NOT Classic Thermite ('light and go')!!!

[Edited on 23-6-2015 by blogfast25]

blogfast25 - 23-6-2015 at 09:21

Old fashioned but very doable on a lab/hobby level: electrolysis of Sr salt watery solution with a mercury cathode.

An Sr amalgam forms. Strip off mercury by vacuum distillation or under protective Ar blanket.

uzaymaymunu - 23-6-2015 at 16:12

Quote: Originally posted by blogfast25

Old fashioned but very doable on a lab/hobby level: electrolysis of Sr salt watery solution with a mercury cathode.

An Sr amalgam forms. Strip off mercury by vacuum distillation or under protective Ar blanket.

Yes! sounds very good

But I don't understand sth: Why it isn't the industrial method?
It looks like cheaper than that:
"The metal is produced commercially by reducing strontium oxide with aluminium. The strontium is distilled from the mixture."

Guys, I'm sorry about my poor english :/

[Edited on 24-6-2015 by uzaymaymunu]

gdflp - 23-6-2015 at 16:29

Quote: Originally posted by blogfast25

While this process is doable by amateurs, I'm not necessarily sure that it is safely doable by amateurs. Vacuum distillation of mercury is quite difficult to perform safely in an amateur setting, especially considering the high density of mercury and thus the risk of condensing droplets cracking the glass receiving vessel.

blogfast25 - 23-6-2015 at 18:12

Quote: Originally posted by gdflp

[...] thus the risk of condensing droplets cracking the glass receiving vessel.

That last mentioned risk is so easy to engineer against, it isn't even worth mentioning. Mercury may be dense but it's also a liquid and thus extremely deformable.

Safety concerns are 'how long is a piece of string?' kind of issues. A bit like 'is it OTC?'. Let the experimenter decide, I say. Anyone who will attempt to prepare metallic Sr has to be a decent chemist or forget about that altogether and that's true of most chemical endeavours worth doing.

Incidentally and not that it matters much but compared to WGTR's scheme, amalgamatic Sr from electrolysis is a walk in the park.

[Edited on 24-6-2015 by blogfast25]

Brain&Force - 23-6-2015 at 19:11

Quote: Originally posted by uzaymaymunu

I read this as "is it possible to *use metallic Sr with catalyzed magnesium reduction method to get potassium."

I don't see why not. But OP, please clarify what you mean.

blogfast25 - 24-6-2015 at 09:26

Quote: Originally posted by Brain&Force

I don't see why not.

Really B&F? Considering how 'goldilocks' the reduction of KOH with Mg powder and t-butanol (assuming this is what the OP is referring to) actually is, there's little reason for optimism to reduce Sr(OH)2 by that method.

phlogiston - 24-6-2015 at 10:08

One method I haven't seen mentioned yet is by thermal decomposition of strontium azide.
Doable on a lab scale, but involves toxic and explosive compounds. However, as blogfast25 remarked, any method to make Sr is going to require some skill.

aga - 24-6-2015 at 11:02

Heat sensodyne toothpaste to 900C and electrolyse, yielding a very small quantity indeed.

[Edited on 24-6-2015 by aga]

battoussai114 - 24-6-2015 at 11:08

Quote: Originally posted by aga

Heat sensodyne toothpaste to 900C and electrolyse, yielding a very small quantity indeed.

[Edited on 24-6-2015 by aga]

Could I chew some strontium for my sensitive teeth too?

blogfast25 - 24-6-2015 at 11:40

Quote: Originally posted by aga

Heat sensodyne toothpaste to 900C and electrolyse, yielding a very small quantity indeed.

[Edited on 24-6-2015 by aga]

Did you mean fluorine?

uzaymaymunu - 24-6-2015 at 14:19

Guys, I have master degree on organic chemistry. And I'm planning to do this experiment in fume hood.

Quote: Originally posted by Brain&Force

Quote: Originally posted by uzaymaymunu

I read this as "is it possible to *use metallic Sr with catalyzed magnesium reduction method to get potassium."

I don't see why not. But OP, please clarify what you mean.

I mean this: Sr(OH)₂ + Mg

[Edited on 24-6-2015 by uzaymaymunu]

blogfast25 - 24-6-2015 at 15:36

Quote: Originally posted by uzaymaymunu

I mean this: Sr(OH)₂ + Mg

How, in which conditions?

battoussai114 - 24-6-2015 at 20:11

Quote: Originally posted by blogfast25

Quote: Originally posted by aga

Heat sensodyne toothpaste to 900C and electrolyse, yielding a very small quantity indeed.

[Edited on 24-6-2015 by aga]

Did you mean fluorine?

Nope, it's indeed strontium. They put Strontium chloride in toothpaste for sensitive teeth... If I had to guess its probably due to how the body assimilates strontium in calcium formations (like bones) due to their similarities.

Ref for the use of strontium in toothpaste: http://www.webmd.com/vitamins-supplements/ingredientmono-107...

uzaymaymunu - 25-6-2015 at 16:40

I'm confused about something:
When you electrolize brine solution, the half reaction on cathode is: H⁺ + e^- ----> H₂
It's normal because reduction potential of sodium ion is -2.7 Volt.
So, I didn't understand why Sodium ions reduce on Castner-Kellner process?

[Edited on 26-6-2015 by uzaymaymunu]

[Edited on 26-6-2015 by uzaymaymunu]

[Edited on 26-6-2015 by uzaymaymunu]

blogfast25 - 25-6-2015 at 17:14

Thanks, Battou.

Quote: Originally posted by uzaymaymunu

I'm confused about something:
When you electrolize brine solution, the half reaction on cathode is: H⁺ + e^- ----> H₂
It's normal because reduction potential of sodium ion is -2.7 Volt.
So, I didn't understand why Sodium ions reduce on Castner-Kellner process?

Only in the mercury cell is Na+ reduced to Na (amalgam).

Not in the membrane process:

https://en.wikipedia.org/wiki/Chloralkali_process#Membrane_c...

It's a good question though and I haven't given it much thought up to now. I suspect it has to do with the overpotential for H+/H2 on mercury. Not sure though...

[Edited on 26-6-2015 by blogfast25]

uzaymaymunu - 27-6-2015 at 02:08

Quote: Originally posted by blogfast25

I suspect it has to do with the overpotential for H+/H2 on mercury. Not sure though...

[Edited on 26-6-2015 by blogfast25]

Why? I think only more than 2.7 V potential, Na+/Na reduction is possible. Under 2.7 V potential, only H+/H2 reduction is possible.
(I'm just thinking loudly, not sure)

blogfast25 - 27-6-2015 at 07:21

Quote: Originally posted by uzaymaymunu

Why? I think only more than 2.7 V potential, Na+/Na reduction is possible. Under 2.7 V potential, only H+/H2 reduction is possible.
(I'm just thinking loudly, not sure)

No. I don't think what you're saying is correct. But I wish someone else could throw some light on this.

Electrochemists of SM, unite!

clearly_not_atara - 27-6-2015 at 10:41

Why not just reduce it with potassium? Assuming you're familiar with producing K, SrCl2 + K >> Sr + KCl should be very favorable.

uzaymaymunu - 27-6-2015 at 12:37

Quote: Originally posted by clearly_not_atara

Why not just reduce it with potassium? Assuming you're familiar with producing K, SrCl2 + K >> Sr + KCl should be very favorable.

Good idea but at which conditions? It's not possible with aqueus SrCl₂ solution.

[Edited on 27-6-2015 by uzaymaymunu]

Molecular Manipulations - 27-6-2015 at 12:48

I doubt that would work, potassium's greater volatility will negate the advantage of the small 'free energy', making separation nearly immposible.

blogfast25 - 27-6-2015 at 13:19

ΔHf0 for KCl and SrCl2 resp. – 437 kJ/mol and – 829 kJ/mol (both NIST Webbook values).

SrCl2 + 2 K === > Sr + 2 KCl, ΔHreaction0 = - 45 kJ/mol. Entropic effects notwithstanding, that’s not promising ('not favourable'). And with K more volatile than Sr, heating isn't a solution here, as MM points out.

[Edited on 27-6-2015 by blogfast25]

uzaymaymunu - 27-6-2015 at 16:49

" The metal can be prepared by electrolysis of the fused chloride mixed with potassium chloride, or is made by
reducing strontium oxide with aluminum in a vacuum at a temperature at which strontium distills off. "
Sauce: CRC Handbook of Chemistry and Physics

Why chlorides, why not hydroxides?
And which ratio SrCl2/KCl should we prepare?

[Edited on 28-6-2015 by uzaymaymunu]

blogfast25 - 27-6-2015 at 17:07

Quote: Originally posted by uzaymaymunu

And which ratio SrCl2/KCl should we prepare?

A eutectic mixture: lowest possible melting point (assuming there is an SrCl2/KCl eutectic).

[Edited on 28-6-2015 by blogfast25]

WGTR - 27-6-2015 at 17:57

Referring to a previous page, here's the phase diagram:
https://www.sciencemadness.org/whisper/viewthread.php?tid=62...

Here's some more detail on strontium electrolysis:

(pg. 62)

For whatever reason, it looks like temperatures given are wrong/sloppy in this reference.

Dan Vizine - 3-7-2015 at 17:32

The electrochemists may well agree with you Blogfast, Hg has a large overpotential for H production. But I'd stay far away from any aqueous solutions

I have a deep-seated distrust of any but a well equipped lab being able to quantitatively remove Hg from a metal lattice. Boiling and condensing Hg in standard Pyrex is old hat, that's what all of our Hg diffusion pumps did back when those were routinely used on vacuum lines. For me, it's a more about how would you know when you had succeeded? Just achieving constant weight, wouldn't mean all of the Hg was out, maybe it was just not accessible. Elaborate, really extreme attempts to remove Hg from black P (catalyzed to form by it and copper-coated steel rods) fails, always.

The industrial method is, as noted, SrO and Al done at high vacuum in long heavy-walled steel retorts. Reactants and heat at one end. At a particular temp. zone, the Sr vapor will condense. It's very difficult for most to engineer at home.

The Downs cell with a molten Sr salt eutectic is the route I'd try at home. It is what Westinghouse called a "Type 2" fused bath electrolysis. In Type II the molten metal is deposited on a cathode that is sufficiently chilled to collect the metal as a solid from the molten bath. Atmosphere control will be paramount in any method.

This is a far more difficult task than making sodium or potassium. That is generally true for group II elements. At one point I was convinced that I'd find a way to make shiny barium metal. I no longer believe that I will succeed.

Does your country allow importation from China? They'll sell you nearly anything. Of course e-Bay, GalliumSource, Metallium , etc. will sell you Sr if your import people aren't ball-breakers (and some countries really are!). But if you are intent on the manufacture, prepare yourself for a work and time-intensive project.

j_sum1 - 3-7-2015 at 19:27

Quote: Originally posted by Dan Vizine

.
At one point I was convinced that I'd find a way to make shiny barium metal. I no longer believe that I will succeed..

Sorry to hear that DV. Your glovebox was looking great and you were showing every indication of solving problems as they arose.
The question then is, has anyone ever produced shiny barium samples? Yours were the brightest that I have seen.

blogfast25 - 4-7-2015 at 07:05

Quote: Originally posted by Dan Vizine

Just achieving constant weight, wouldn't mean all of the Hg was out, maybe it was just not accessible.

Hmmm... the method is still used, albeit rarely now, for gold extraction for example.

There's an old sample of Ca metal in the British Museum, prepared all these decades ago with the aqueous amalgam cathode method. I'd have a go at that, if I had enough mercury.