Crystallization of sodium acetate - GIF

[Altair]

Crystallization of sodium acetate.




Previously:

Timeline of chemical element discoveries - photo
Briggs-Rauscher oscillating reaction demonstration - GIF
Floating an anvil in liquid mercury - video
1930s Neon salesman's sample case - photo
Elemental gases in front of a Tesla coil - GIF
Gallium in water - GIF

[nova_robotics]

If we had a video of this on a thermal camera it would be an even better show.

[hemmjo]

I am curious what it the real time interval for that?

[nova_robotics]

I am curious what it the real time interval for that?

That video is realtime.

Edit: I meant to say the video isn't sped up. Words are hard.

[hemmjo]

I recall an activity from a LONG ago physics class where we melted some white solid material, I do not remember what it was, then it cooled but did not solidify. When we touched it with a toothpick and it hardened almost instantly.

Is that what is going on here? or is that a saturated solution waiting for someplace for the crystals to form?

[nova_robotics]

I recall an activity from a LONG ago physics class where we melted some white solid material, I do not remember what it was, then it cooled but did not solidify. When we touched it with a toothpick and it hardened almost instantly.

Is that what is going on here? or is that a saturated solution waiting for someplace for the crystals to form?

Might very well have been the same stuff.

This stuff has been heated to melt it, then cooled off again. Going by the temperature it should have solidified, but it can't due to a lack of nucleation points. The crystals can't grow without nucleation points, so it just stays a liquid. It's like having super pure water, in a very clean and smooth container. If you're careful, you can cool that way below 0C/32F and it will stay liquid. Now it's a supercooled liquid just waiting for some nucleation point or shock. When the material gets the nucleation point it needs to allow crystals to take hold and begin forming, the whole thing crystallizes and turns to a solid.

What you can't see from the video is this thing releases a ton of energy when it crystallizes. As soon as you put that poker into the liquid, or even give the container a good flick, it will get HOT. There's a ton of potential energy here that all gets released when the material goes through a phase change (latent heat of fusion), which is why this material can be used as a thermal battery. You just throw them in boiling water to recharge them. Very cool.

[hemmjo]

A yes, like those "instant heat" packs you can get got cold weather activities etc. A plastic pouch with liquid "stuff" in it. You click s little disk that is inside the pack, and it solidifies, giving off heat to warm your hands etc.

[nova_robotics]

A yes, like those "instant heat" packs you can get got cold weather activities etc. A plastic pouch with liquid "stuff" in it. You click s little disk that is inside the pack, and it solidifies, giving off heat to warm your hands etc.

Yup, that's them. I've been wanting to build a thermal battery for my house for ages. I have geothermal and evacuated tube solar to produce heat. But the solar is intermittent, and I live in the frozen winter hellscape of Canada. You can use bricks or water to store energy, but that's linear in its cooling. The temperature goes down as they lose heat energy. So there's almost no heat coming out of the stupid thing by morning. Thermal batteries are not linear. They maintain a roughly constant high temperature until they're pretty much depleted, then the temperature crashes. This is way more useful. Both parafin and sodium acetate are interesting candidates for a thermal battery.

[Moldyjim]

Ah... Sodium acetate not only a heat battery, it's also the flavoring on salt and vinegar potato chips.

Really cool material.

[mwmkravchenko]

Yup, that's them. I've been wanting to build a thermal battery for my house for ages. I have geothermal and evacuated tube solar to produce heat. But the solar is intermittent, and I live in the frozen winter hellscape of Canada. You can use bricks or water to store energy, but that's linear in its cooling. The temperature goes down as they lose heat energy. So there's almost no heat coming out of the stupid thing by morning. Thermal batteries are not linear. They maintain a roughly constant high temperature until they're pretty much depleted, then the temperature crashes. This is way more useful. Both parafin and sodium acetate are interesting candidates for a thermal battery.

There are heat storage tanks that use paraffin wax as the thermal storage. Might want to rig up something like this? Near Ottawa by the way. Canuckistanies we are.