Name: 鎂在水中的燃燒 - 視頻週期表 (Burning Magnesium in Water - Periodic Table of Videos)
Uploaded: 2021-01-14T10:17:13.000Z
Duration: 8 min 8 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

關係子句

don't say your reaction, which I didn't know could occur.

The reaction between magnesium and water, The reason why I didn't know it could occur is quite simple.

I've got a piece of magnesium ribbon and some water.

You see that if I add the water, absolutely nothing happens.

I didn't really think whether magnesium could react with water.

However, Neal has done some quite exciting experiments, which Brady has videoed in slow motion.

So what Neil did was to take bits of magnesium, set fire to them in air, so they were burning really brightly and then gently lower them into a large container of water.

As with all his experiments, he began on fight a small scale.

You can't see the water very well at all, but you can see the magnesium as it comes in.

What I found really quite surprising is that the burning magnesium continues to burn underwater.

In fact, bits of it start coming out of the water again, breaking off, and that came to be the real surprise to begin with.

But then I realized that the magnesium is pretty holt close to its melting point.

Its melting point is only 650 degrees centigrade, and in fact, in some of the shots, you can see bits dropping off the magnesium even before it gets to the water, because it's melting when it goes into the water, you have a very clean surface of magnesium.

There is no oxide layer to protect the magnesium, as there is in the water that we've got here, where the magnesium is coated in a layer of rock side.

So it's insulated, if you like from the water.

So you have a very high temperature water and clean magnesium on dhe, so you can get a reaction of magnesium producing magnesium oxide and hydrogen.

It maybe magnesium hydroxide, but you will get hydrogen so you have an extra thermic reaction making the magnesium oxide or hydroxide, and you're producing hydrogen, which itself can burn and could cause a minor explosion.

It's a bit like sodium, but not quite so violent.

Neil then tried it on a bigger scale, and there it's really nice.

You can see as the magnesium goes close to the water surface, you can see its reflection coming up to meet it, the reflection of the burning magnesium on.

Then there is a few seconds of video, which was much shorter time because it's been slowed down in reality.

Then there is really quite a violent reaction on pieces of burning magnesium fly out.

In fact, some fly out completely outside the container.

Being Neil, he tried an even bigger piece.

Then what happened is that again you see the burning magnesium approaching its reflection on Once it goes in, you get a really violent reaction.

There is quite a nice red color that is formed.

Whether this is the emission from hot magnesium atoms, we've seen these sort of emissions in the reactions of rubidium and sodium, or whether it is just the hydrogen gas burning.

Because we've also seen in some of the videos that hydrogen gas in the absence of excess air will burn with the reddish color.

But there is a quite a nice register color formed as well.

I'd never seen the reaction off magnesium with water on dhe.

It is the high temperature and the fact that it's liquid that is causing this reaction to take place.

If you look at the periodic table, calcium reacts quite easily with water.

Calcium is the element immediately below magnesium, so it's not surprising that magnesium also reacts with water.

But chemist usually forget that I did ask Neil White had ever tried this experiment, and the answer is that he was burning a piece of magnesium in these fume company, and the fire got a bit bigger than he really light.

So he put it into some water and his amazement.

So the real take home message for all of you is that if you have a metal fire, the last thing you want to do is to put water on it.

This is probably why, during the World wars, people use magnesium bombs as incendiary devices because once the bomb starts burning, you can't put it out with water.

If ever You're working with metals at high temperature and they start burning, use sand.

If we scraped the oxide off, that piece of magnesium ribbon wouldn't react with the water at all.

I wondered myself whether this would happen.

My feeling is that they might be a reaction, but it would be pretty slow.

That is, if we clean the magnesium, perhaps electric chemically Well, something like that.

Eventually we might see a few bubbles of hydrogen, but it's partly the high temperature, the molten metal that really gets the thing to take off.

So if you'd like to see another great magnesium reaction, you can see the video we made a little while ago of magnesium reacting with solid CEO to again.

Magnesium is extracting oxygen from a molecule CEO.

To that, we would normally expect to be pretty stable.

The difference between its reaction with water and sea or two is that the carbon it leaves doesn't burn.

 The hydrogen adds a little vent to the experiment. 