don't forget that even tho entropy is going down when you begin to release the potential energy in the hand warmer you are increasing the entropy in the environment around you

These were a really fun use of the thermal imaging camera.

@IstasPumaNevada

7 жыл бұрын

I haven't found an exact price for that camera, but I found a similar model number listed at $40,000. This has no bearing on how fun it is, I just found that interesting and wanted to share.

@icaru34

7 жыл бұрын

I remember being handed a thermal imaging camera with the words "this is 20 thousdand dollars, don't drop it"

The entropy may be decreasing when you from solution to crystal, but the heat released by crystallization causes an overall increase in entropy due the random thermal motion of all the particles heated up by the hand warmer.

This channel deserves more credit!

It got a lot clearer to me when it was stated it's potential energy. Great video! Love that you upload extra content from the interviews!

Gibbs free energy if anyone is wanting an equation explanation for the entropy thing. "G = ΔH - TΔS" where S is entropy and H is enthalpy. Entropy is the randomness the professor was talking about. G must be less than 0 for the reaction to take place. So for this reaction, at room temperature G is negative because ΔH is bigger than TΔS but if we increase T then "TΔS" becomes larger (because T and ΔS are being multiplied together) than ΔH and G becomes positive so the reaction goes the other way. Quite a neat little equation I think.

@Croxmata

7 жыл бұрын

I'd describe entropy as "disorder" rather than "randomness".

@Malandirix

7 жыл бұрын

The professor used both but yes, I'd agree that disorder is a better way of describing it.

@hectors03

7 жыл бұрын

Common guys, we are all smart people. We know the best way to describe entropy is the "number of micro states occupied"

Thanks for the extras Brady! I wondered if Entropy had anything to do with this.

@IstasPumaNevada

7 жыл бұрын

Entropy has a hand in everything. In fact, I'm increasing it right now by typing this comment. :)

the energy is in the bonds! When you sodium and acetate are put back togeather, the bonds reform. Because the sodium acetate bond is STRONGER than the bond between NA-OH and CH3COO-H. The stronger the bond, the more the energy is released. The weaker the bond, the more energy is stored in it!

A better description of entropy is the number of ways in which the components of the system can be arranged.

are those Snatoms that Sir/Prof Poliakoff uses near the end of the video? Shoutout to Dirk from Ventrasiblium! ;)

Entropy is crazy :) sometimes does not fallow intuition because of the environment... maybe lol

My hand warmers list their ingredients as: iron powder, water, salt, activated charcoal, and vermiculite. I was wondering how they work. By the way, they keep producing a comfortable heat for hours.

I bet Phil would like to give his comment on this :D

So, if you shock the saturation, will the crystal start? IE: slap or thump the package...

Wonder if clicking the metal disk would cause the process to begin if you boiled the bag, let it cool to room temperature then cooled the bag sufficiently low enough to cause it to freeze, assuming one could actually cause the metal disk to click in the frozen solution? Would the fact that the solution was frozen defeat the action because the solution is crystallized preventing the molecules from combining and reentering together?

I have 2 questions; 1. Where does the seed go after you have boiled the hand warmer back to its 'safe' state? You mentioned the seed could be a piece of metal or crystal, surely that would still be floating around in there and restart the process. 2. The larger piece in there, the clicker, doesn't act as a seed. What is it made of? Thank you to anyone who answers.

@jackwhite3820

7 жыл бұрын

My guess is that the metal piece is simply stainless steel, and when you 'click' it, it causes a cavitation bubble, which when it collapses causes enough disturbance to initiate nucleation. But that's just what I think is going on; don't have anything to back that up.

Respected sir 🌟, can we do this same experiment with sodium chloride?

Does the volume/density of the hand warmers change as they react?

@subliminalvibes

7 жыл бұрын

The Killer Spud No, they don't lose or gain mass, volume, or density. They simply crystallize. 👍

@IstasPumaNevada

7 жыл бұрын

+subliminalvibes Can you point me to a source on that? I'm having trouble finding information specifically on sodium acetate, but have found that the volume of a substance and a solvent don't necessarily simply add when mixed.

@subliminalvibes

7 жыл бұрын

I mean to the naked eye and to the touch... I wouldn't know if they do this on a molecular scale but if there's some kind of rule regarding this phenomenon, then I've not heard it regarding sodium acetate. I think if the question was, 'All minerals do X, so does anyone know how much of a factor sodium acetate does X by...?', then I wouldn't have answered. 😊

@IstasPumaNevada

7 жыл бұрын

subliminalvibes If it does happen, it may be detectable by touch. The human hand is very sensitive.

@jackwhite3820

7 жыл бұрын

I would argue that it would be a remarkable coincidence if the volume stays the same. Sure mass is conserved here, but claiming that the volume of the ion-water complex is equal to the volume of the crystallised salt plus the water, requires some explanation. For example this must surely depend on the salt and it's crystalline structure, like is it body-centeredcubic or face-centeredcubic, that has an effect on the density of the crystals, and how big are the salt ions in comparison to the water molecule, because that has an effect on the density of the dissolved solution. And I'm sure there are more factors, which won't be the same from salt to salt.

? is the sound a little muffled ?