Australia's Science Forum

Hi All and a belated Happy New Year.
Can my colleagues advise me as the whether it is safe to leave elemental mercury exposed in a petri dish in a room overnight? The MSDS does not specify its use to this degree.
Cheers,
Robyn

I Would NOT, if the cleaners or any one else was to bump it over etc. You would have to have signs telling people want it is etc. Also I would not like to be the room with Mercury it is very toxic.

Taken from page 155 CSIS Volume 2 Apprendices D

Most mercury compounds are highly toxic if ingested or absorbed through the skin. Good Laboratory hYGIENE AND PRACTICES WILL ESSENTIALLY ELIMINATE EXPOSURE RISKS.

I'm pretty sure the vapours are just as bad as touching it. I remember reading it somewhere but don't have time to look it up right now, but you are supposed to wear a mask and avoid breathing it when you clean it up if there is a spill. It is another reason you shouldn't let it sit if it spills, and make sure you get every tiny drop when it does...

Just curious - why would you want to do that anyway?

Physics teacher wants to do something about a mercury motor? That's all I know at this stage.......

You can buy mercury switches/diodes? from Dick Smith. They are a little glass bulb with a dollop of mercury inside, and two wires protruding. They are used for testing conductivity of elements and materials. If this is what the teacher wants to use the mercury for, then these little things are a much safer idea, than a dish of mercury which does have toxic vapours.

Thank you all for your advice. I am not happy leaving it lying around, too. Must get in some more mercury decontaminant as well.
Thanks dime - will look into your switches as well, sincerely hope they will substitute.
~Robyn

Is it the faradays experiment where they put a magnet in the bottom, 2 wires in the mercury, and it somehow makes a motor? I haven't seen how the whole thing works but our HT likes that one. Lost our entire stash of mercury one year when he had the beaker sitting on the base of the retort stand half full of mercury, and proceeded to DROP the magnet into the beaker. Said beaker broke (surprise, surprise), mercury splashed EVERYWHERE travelling several meters along the floor and around benches and I was called in to clean up while he went on with teaching his class!!

Dear Rosalie,
yes, it sounds by your description that he is using the mercury for Faraday's experiment.
What a shocking time you had with your spill, really hope you got it all cleaned up. Will double my decontaminant order!!!!
Robyn

You don't have to leave it out if that's the case. Just send the bottle of mercury and make sure the magnet goes in whatever is used before the mercury goes in! Even plastic can crack if something is dropped on it. I wouldn't be taking any chances. And make sure the teacher pours it straight back in your stock bottle as soon as it is finished with. Mercury is one of those 'cumulative effects' chemicals, so the less exposure time the better. Just make sure the teacher knows the risks and potential consequences if he/she fails to comply! Feel free to use my teacher as an example to back up your concerns

Rosalie, will do thanks!

Hi All,

If for whatever reason Mercury needs to be left out in a small dish, simply pour a layer of water over it and it can then be safely left. When Merc then needs to be used pour off the water into a hazardous waste disposal bottle and use a tissue then to simply dry off the remainder of the water. Gloves are to be worn naturally and there you have it... Ready to use Mercury again and again.

If the Mercury is to be used as a faraday motor, I will ask the mrecury and apparatus to be moved into a working Fume cupboard, as the electric current used to produce the motor effect also produces heat and invisible vapour IS released during this part of the experiment.

Cheers,


Robb.....