Hi there, first post so - Short version, I'm a professional Microscopist and I do science outreach for kids.
I've got a session coming up at the end of the month and I'm doing a practical session on the reaction of calcium metal with water as it's the most
reactive chemical I'd dare let anywhere near a bunch of children ( I will be demoing sodium behind a safety screen though )
Nice shiny metal, bad habit of going grey and crumbly in exposure to air but how long does that take?
I assume the 50g zip lock bag I opened a week ago will be ok as the oxygen inside will be quickly depleted but if I put single granules of the metal
into 7ml screw top bijous and close them up, how long will they be good for - will they be ok for a week or do I have to think about prepping them the
night before? diddi - 13-5-2016 at 01:39
calcium goes off pretty quickly. I keep under argon and even then it is not that bright. you can store under a light hydrocarbon like hexane
perhaps? Sulaiman - 13-5-2016 at 01:53
Might it not be better to show the corroded surface as an example of its reactivity with air,
then cut through to show shiny metal, just as with sodium etc.
Some phenolphthalein in the water for Na and Ca may stimulate interest.Scalebar - 13-5-2016 at 02:26
Might it not be better to show the corroded surface as an example of its reactivity with air,
then cut through to show shiny metal, just as with sodium etc.
Some phenolphthalein in the water for Na and Ca may stimulate interest.
Calcium's a bit of a sod to cut, especially with granules. I might hedge my bets and keep some under the same oil I use for sodium, or just order
another batch for the day - it's not expensive.
I'm planning on using cabbage water as an indicator as it ties in with some of the kitchen chemistry sections
Aside from chemistry demos and getting bismuth out of lead, does metallic calcium have any uses?
cheers
myristicinaldehyde - 13-5-2016 at 11:23
If it helps, I noticed that my Li foil blackens to what I assume is LiN in mineral oil after about a month. I would keep the Ca under oil too. (If you
have any extra, I'd like some! )
You can use calcium to make an exotic equivalent of a Grignard, or (I think) for reductions. elementcollector1 - 13-5-2016 at 12:16
The Ca metal I have has darkened, but stayed remarkably stable for the past 2 years. It's not corroded significantly beyond the surface - cutting it
gives clean, shiny metal. And this is with no protection whatsoever - just calcium lumps in a plastic bottle. So, as long as you keep it dry,
I think it can be stored for quite a while.Scalebar - 14-5-2016 at 00:31
Great! I just remember in my youth nicking some from a chemistry lesson - wrapped in tissue and hidden under the bed it doesn't last long.
It makes for an interesting burning metal demo - a microtorch gets a few grains going on a refractory block and the flame is a red, it does tend to
spatter though.
)