Andrew Szydlo brings chemistry to life with his spectacular demonstrations, public lectures and TV appearances. In this TEDx talk, Andrew aims to promote chemistry as the science of remarkable changes, which are often overlooked yet so important in our everyday life.
Here is the full text of Andrew’s talk titled “25 Chemistry Experiments in 15 Minutes” at TEDxNewcastle.
Andrew Szydlo – TEDx Talk Transcript
The science of chemistry has disappointed many people.
It disappointed the emperor of China in the year 59 BC. He had been told that one of his court officials, Liu Xiang, could make gold. A great feast was organized, at the end of which, Liu Xiang was to prepare a small quantity of the precious metal.
After toiling away with complicated apparatus for several hours, all he succeeded in producing was an unpleasant smell. Liu Xiang was executed on the spot.
This true story reflects one of the problems which has confronted mankind since the dawn of civilization, the problem being understanding how substances change into different substances. This phenomenon of substances changing into different substances has now evolved into the grand science of chemistry.
So, what is chemistry?
Chemistry is the science of substances and how they turn into different substances. And very frequently, we can recognize a chemical change because there is a change of color.
As I pour my chemical water from one flask into another, you will notice a color change, and this is because I am making a new substance on every occasion.
Chemistry plays an important, a hugely important role in our everyday lives. Masses of substances and materials that we use on an everyday basis owe their existence thanks to the science of chemistry: plastics, polymers, dye stuffs, detergents, perfumes, toothpaste, pharmaceuticals, fuels, explosives.
A whole range of remarkable substances – tap water, fizzy drinking water, masses of substances, fertilizers – owe their existence thanks to the science of chemistry. Chemistry, the science of substances and how they turn into different substances.
Now, here I have showed you some experiments with chemical waters, and I’ve Illustrated for you the principle of what chemistry is about, substances changing into different substances.
I am now going to move to a different type of water, which I have in my container here. This type of water – which is by magicians called magic disappearing water – I will pour some into my beaker here, and I will now throw it into the air and show how it disappears, and I will stand under it there.
And don’t look for it, you won’t find it. And the reason is, it has disappeared into thin air. Why has it disappeared into thin air? Because that is what it is made of.
This liquid, which I have here, represents one of the greatest triumphs of the science of physics. Physics is the science of matter and energy, and one of the greatest challenges of the science of physics in the 19th century was to be able to achieve temperatures which are low enough to turn the gases of air into liquids.
And what I’ve got here is liquid nitrogen, and the liquid nitrogen has a boiling point of -196°C. Now, as you see, it’s boiling away in my plastic bottle here, and the reason why it’s boiling away is because this room is remarkably hot compared to the temperature of the liquid nitrogen.
We here are at about 21-22°C. Liquid nitrogen has a boiling point of -196°C, which is almost as cold as you can get anywhere in the universe. Absolute zero, the coldest temperature in universe attainable theoretically, is -273°C.
Now, one of the golden rules when you have liquids which are boiling is never ever put them into containers which are tightly sealed. That’s precisely what I’m going to do now.
I’m now going to have these Sprite bottles here, and I’m going to tightly put the stoppers on, and I’m going to gradually put them into these dust bins here. Now, the reason why you should never ever do this, is because when liquids boil, they undergo a huge coefficient of expansion by a factor of about 800.
I have poured in approximately 100 cm cubed of liquid nitrogen into each of these bottles, and that 100 centimeters cubed will expand into about 80 liters.
Now, these bottles have a volume of 0.5 of a liter, and therefore, when that liquid nitrogen evaporates, it will occupy about 80 liters; it will generate a pressure of about 160 atmospheres.
Now, these bottles – very clever though they are, made of brilliant polymers – they will just simply not withstand that pressure, and therefore they may explode. They don’t always explode, but when they do explode, the noise is really quite substantial. And that’s why, for safety reasons, I have popped them into the bins.
Now, that will continue to boil away. You may hear very loud bangs, so please be warned, but in the meantime, I’d like to show a couple of fairly obvious experiments with liquid nitrogen, the most obvious one being, of course, to freeze some water.
Water freezes at 0°C. And I will pour a small quantity of water into here and cover it with liquid nitrogen. So, there goes our water there. And I shall now pour liquid nitrogen on it, and that will obviously turn the water into ice.
Now, unlike the experiments which I did with my chemical waters when I mixed chemical waters which were colorless together and you saw a color change because a new substance was being made, here we have a totally different type of effect.
You see there is no color change at all, and that is because here, we have a physical effect. The two colorless liquids, which I have mixed together, are now changing their state. One of them is changing from the liquid state to the solid state; that is the water.
And the other one, the liquid nitrogen, is turning from the liquid state to the gaseous state. So, here we have the three states of matter in one very straightforward experiment.
Now, as the liquid nitrogen continues to boil away, you may hear a slight crackling sound. Now, this is because, when water freezes, it expands slightly, and as it it expands, the crystals take up a greater volume, and they push against one another, and they set up enormous mechanical forces, which is what the crackling is about, and sometimes the beaker may actually crack.
So we shall keep our eyes on this, allow the process to continue, and I can just hear the beginnings of a crackling sound.
Now, I just top it up, make sure we continue to freeze our water. And I wanted to tell you that when liquid nitrogen was first made, at the end of the 19th century, it did set off an entirely new era in the history of technology, and that’s liquid gas technology. And thanks to that, today we have frozen food, and we have a huge number of all sorts of effects that we benefit from; among them, of course, are refrigerators.
Now, to continue then on our experiments – and also the science of cryogenics. To continue with our experiments with low temperatures – these, by the way, approximately five to six minutes, you’ll hear the bangs, so please be warned.
I’m now going to show you an experiment with a solid. Here we have a piece of rubber tubing, and it’s elastic. The reason why it’s elastic is because, when you stretch it, it returns back to its original shape.
Now, the reason why it’s elastic is because – I can hear the pressure being taken up, so you may hear a bang shortly. Now, the reason why it’s elastic, from a thermodynamic point of view, is because it’s very warm in here. (Banging)
And because it’s very warm in here, these molecules in here have lots of energy. However, I will now place the rubber tubing into liquid nitrogen, and please observe carefully what happens as we lower the temperature. And you’ll notice this most interesting effect of a shower, a shower which is issuing from the end of the rubber tube.