Overdid It

Hard to find quality time to post this year.

Chemistry Demonstration today. Previously, sodium acetate crystalisation had been quite a problem, as they did not crystalise fast enough. We hypothesized that it was because it was not supersaturated enough.

Being in charge of the sodium acetate crystalisation reaction today, I dumped a layer of sodium acetate into the beaker and added a few squirts of water to it. Now, that should supersaturate it...

As the magnetic stirrer whirled and the temperature rose, the salt started vanishing into the water, and before long, it was clear again.

So I added more sodium acetate, then it became clear, and I added more, and it dissolved and I added more...

When we poured it out for testing, it worked wonderful. A few drops of sodium acetate froze in the positions at which it hit the glass dish, and as more drops pounded onto it, a pillar was formed in no time.

Pouring the solid back into the mixture of heating sodium acetate, I added more sodium acetate, just in case.

Till now, a transparent tough-looking film was forming on the surface, indicating that it was supersaturated, but when we increased the angular velocity of the magnetic stirrer, the current disrupted the film.

No more film? Add more acetate.

We switched off the heat and went to look at the other group presentations.

Supersaturated sodium acetate was trouble, every now and then the surface turned into a blanket of white salt. And we had to heat it and stir it again. Timing was crucial.

And hard to manage.

We did not have time to practice our presentation once through, so when I moved the sodium acetate off the hot plate, it did not cool down fast enough before it was time to pour it. However, due to the overly supersaturatedness of this wonderful solution of destruction I have boldly concoted, it crystalised quite fast even at an uncomfortably warm temperature.

Do not forget. This is hot ice. Crystalisation of it is highly exothermic. Until now, we did not really consider the amount of heat released as a function of the concentration of our solution.

Unexpectedly, as the sodium acetate shot needle like spicules from nucleation centers, the crystalisation contagiously spread throughout the tiny existence of the puddle of sodium acetate. As we all know, this was an exothermic reaction, and especially when the solution is so saturated that crystals can form under a turbulent current and high temperature...

You can see how overly supersaturated that would be.

Like nothing has happened, the puddle disappeared the moment I turned around. Upon probing with the glass stirrer, the hot ice had burned away and melted the plastic sheet and fell into our 'dormant volcanic liquid'.

Shouting "Hey look everyone we melted the plastic" would not have been a very good cover up for my blunder.

I tried to see if there was any more sodium acetate left to 're-do' it. Oh my, the liquid in the conical flask has started to crystalise too. If there was any chance of find out any more was left...

I tipped the conical flask over and dripped a drop of sodium acetate onto my hand.

Since hot liquid + exothermicness = very hot, with the assumption that it could melt plastic, and the liquid crystalised upon touching my hand; the result was a rather embarassing turn around, mouthing of not very nice language and slamming my hand onto the lab bench repeatedly like I was a lunatic trying to kill an invisible cockcroach.

The high supersaturation had made the crystalisation a lot MORE exothermic than what we have tried...

Around 5 times more unexpected.

It crystalised so well that instead of shards of crystals that could be washed off, it turned out to become a plate of solid white which clings onto the glass, which only way of clearing would be to melt it.

Our elephant toothpaste lava did not go quite well either, due to some mix up in our requirements, we used 6% instead of 35% hydrogen peroxide, so no one saw our lava.

Probably the only thing anyone saw throughout our demonstration was the plastic melting effect of volcanoes. Not very exciting.