Sciencemadness Discussion Board

How to stir solution with iron filings on a hot plate stirer?

Lion850 - 22-12-2019 at 23:22

I need to stir a beaker with iron filings and iodine in water on my hot plate stirrer. Using a standard PTFE coated stir bar results in all the iron filings sticking to the bar. I though the iron filings would move around on their own (without any stir bar being thrown into the beaker) when the stirrer is turned on but they do not. My question is how can I get the iron filings moving around (other than boiling)? This reaction can take hours so manually stirring is not an option.

j_sum1 - 22-12-2019 at 23:37

I recall (early) nurdrage usung a paperclip once but I think the paperclip was the reagent.

Stirring from the top would seem to be the most logical option but if you are committed to magnetic stirring you might experiment with different stirrer geometries. One of those cross-shaped ones with large paddling action might work.

Or, here's an idea: no idea if it would work. Mould your iron filings into pellets using something that will eventually dissolve or disintegrate. Maybe even fashion them into a stir bar and magnetise it.

Perhaps more practically, see if you can devise a way to stir by bubbling an inert gas or air if it is appropriate.

If I am following your work correctly, you are aiming for iron III iodide. Good luck.

Lion850 - 23-12-2019 at 00:49

Hi j_sum1 thanks for the suggestions. I actually just finished in the shed and it seems the filings reacted OK with the iodine even though they were stuck to the stir bar. But I still would prefer them swirling around in the solution :)

I think I made Iron (ii) iodide FeI2? I'll post a report in the usual forum and hopefully some member more knowledgeable will comment.

Mush - 23-12-2019 at 04:47

With a help of an overhead stirrer.

PirateDocBrown - 23-12-2019 at 11:25

A couple ball bearings?

SWIM - 25-12-2019 at 18:57

Wait a minute...
If the stirbar is rotating and they're stuck to the stirbar they are moving.

They may be stuck to the bar, but they're being dragged through the solution forcing new material into contact with it while the rest of the solvent is being stirred.

Are you sure that's not sufficient?

This isn't a rhetorical question. I really don't know if these two situations are all that different or not.

Lion850 - 25-12-2019 at 21:53

Hi SWIM the reaction did in fact proceed so I think as you say although stuck they still move through the solution. I initially thought there was a lot of iron left over, that did not react, but in fact I got a reasonable volume of product so it certainly worked to some extent.

AS mentioned by a few users stirring from above is also an option.