This used to be a huge environmental problem.

We're going to demonstrate it to you in the lab and we're going to do it with a piece of kit which I inherited from my late friend David Jones.

We got the kit, but not the instructions, but Neil worked out how to use it.

The problem of acid rain is that in the 19 sixties 19 seventies, people were burning fuel, particularly cold, that contained a lot of sulfur.

They were burning it in their homes, in power stations, on dhe, even at one time in trains, in railway locomotives, on dhe, when their cell for containing cold burns, it generates s 02 which is a gas, and sometimes s 03 which is a solid but it's generated is fine particles in the air.

And then when it rains, thes gas s 02 and s 03 dissolve in the water to give either self euros or sulfuric acid.

Acid rain has called huge environmental problems, particularly killing forests, because trees like pine trees and so on normally do not grow on very acid soil on.

We're talking about really quite acidic rain on the east coast of the United States.

Some of the acid rain had in acidity of pH between that of lemon juice on battery acid.

So the experiment consists of a large container in which you can burn sulfur to generate the S 02 arrests of three.

It then has a vessel on top in which you can put water in, and the water is sprayed out of some glass arms so you get rain going into the gas.

The problem is, of course, you can't see whether the water has become acidic if you just use plain water, so you have to put in indicator, He added a tiny bit of potassium hydroxide, which made it nice blue color.

And if it gives acidic to turn right run Number one.

Neil was unduly modest.

Put in just a little bit of sulfur wasn't enough.

It rained, but no acid.

So next time Neil let himself go and put in a large amount of sulfur birth Well, in fact, it caused fog inside the container.

That's rather interesting, because when people burnt CO with sulfur in it, we used to get terrible smokes.

People couldn't see their feet when they were basically because the smoke was so thick.

Experiment then worked really nicely.

You could see the water going down, forming raindrops, and as the drops fell, they went from blue to red.

Brady was quite courageous.

He put his camera in the water.

You concede the raindrops coming down and eventually it was.

But don't worry, thank you way really like the demonstration.

And I think the important thing to know about acid rain is that it waas a huge environmental problems.

But it is one which chemists and engineers have succeeded in more or less solving domestic fires.

These of heating and houses now uses cold, which has had the cell for removed and in large power stations.

They take the flue gas that comes out of the boilers on decell fries it usually by reacting it with lime, the Esso to reacts with the lime to make calcium sulphate, which is innocuous.

It can just be put to landfill.

Nowadays, most power station, certainly here in the UK, use natural gas methane rather than coal, So the amount of limestone that is being used for diesel for ization is going down for it substantially.

But if you went out for a stroll in that romantic looking missed hanging over the trees around the lake, the chances are that you would be breathing in a dilute fall of sulfuric acid.

Acid rain was not a big issue here in the UK because most of the S 02 was injected quite high in the atmosphere on blown overto mainland Europe, where there's much more forest than in the U.

K Tour Chimneys throws sulfur laden exhaust high into the air.

And it had really quite significant effects on the forests in Germany on dhe northern Europe.

It comes from Mobil's eastern and Western Europe, but due to the prevailing winds may be around 50% comes from Great Britain.

When I first came to noting him, on some days, you could taste the S 02 in the air, the removal of the air.

So too, has had one bite, strange effect that Nottingham was famous for growing roses, and it turned out that the S 02 in the air was very good at killing the sum of the mildew and other pests that can grow on roses.

So when the air was cleaned up, the roses started getting all of these pests.

And now the rose growing industry round Nottingham has more or less disappeared.

Would you like to learn more about raindrops?

How about the shape of raindrops?

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