Australia's Science Forum

A teacher wants me to work out how much Na metal to put in water for a demo to make it look impressive but not dangerous

Any suggestions?

not much!! and don't use glass!!! You just need a tiny amount on the tip of a scalpel. It depends on air temperature, humidity etc as to what happens. Sometimes you can use a piece and not much happens and on a different day the same amount will burst into flames with a bang. I'd say be prepared to give it a few goes. Start small and gradually increase the size. The kids will enjoy watching it more than once anyway!

Do a search for sodium metal there is quite a bit on it there

I got a new batch and its very reactive
A match head size put a ding in our safety screen and filled the room with smoke!
Nail size made a huge bang and hit the ceiling and left a mark
becareful and all wear safety glasses

One of the teachers here puts small bits in water in a glass dish on an overhead projector. He then drips some phenolphthlein in as well. It projects quite well.

It depends on whether this teacher is a good guy or not!
Do you want revenge on him?

lol thanks guys, I think we'll start small and go from there. Will do a search for past threads.
I better not blow up the tacher, she is the HOD and a good guy and only one of two qualified science teachers here, the rest just teach science

We always do ours outside if after the big bang factor .
We use a icecream bucket to do this in than when gets a crack in it it is easily replaced.

Have fun!!!!!!!

KIMMY

here at my school the teacher make that discsion of how much to use.
They do it in the fume cupboard and experiment with the size from small to big.
but guess whose left to clean the fume cupboard after...................
but it is brilliant to watch

Do a demo in the fume cabinet.
I use cold water in a steel tray.. not alumunium... use one of those geology or disecting trays.. that way.. the baby-pea /pea sized pellet of sodium can skit over the water as it burns.. quite impressive

HI All,

To give you an accurate guide, 5mm square pieces will do you fine. This is not enough to generate enough H2 gas to cause any problems.

Cheers,

Robb.....