hot ice with sodium acetate

[strammy]

well today I tried the experiment with sodium acetate and water but it didn't work.

I used sodium acetate from a chemistry lab (so it is pure...), I put sodium in boiling distilled water for a super-saturated solution: 160 gr in 30 ml of water and I left it on the heater for some minutes.

i put the solution in fridge but the solution crystallize in few minutes instead of stay fluid and i cannot use for make instantly "hot ice"...

where I made a mistake?!?

 

thanks a lot!

[DrP]

I think that you need to make sure there are no nuclation points anywhere (like undisolved crystals in the supersaturate, or scratches in the glassware). However, I haven't actually done this experiment myself, but have seen it done and own warming devices that use he reaction for heat. You can reverse it by heating it up and re-disolving.

 

Finally, which is what moved me to post, is that you shouldn't assume that your reagents are pure simply because they come from a chemistry lab. They could become contaminated anyhow. In this instance, though, I'm not sure how it would effect the reaction.

[hermanntrude]

if you're having trouble with it crystallising too soon, just add bit of extra water, and make sure all your glassware is clean and free of cracks and dents

[John Cuthber]

Filter the solution while it's hot (obviously, this might be tricky). That way you remove dust and such that can act as a nucleation point.

[dttom]

A rapid cooling is required for supersaturated solution.

[strammy]

thanks a lot! I'll try all the suggestion and I hope to come with something positive!