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在需要灭火的时候水非常有用
Water is really useful when it comes to putting out fires,
这就是为什么我在做与火有关的事情时
it’s why I always have a bucket of
总是在工作室准备一桶水的原因
water in my studio when I’m doing stuff
但这又是为什么呢？（水可以灭火）
with fire, but why is that? Well,
火的三要素包括了热量 燃料和氧气
it’s the fire triangle: so for a fire, you need heat, fuel and oxygen
当你用水浇灭火的时候
and when you douse a flame with water,
你将三要素中的热量移除了
you’re removing the heat component of the fire triangle.
为什么水擅长做这个呢？
Why is water good at that?
因为水有很高的比热容
Well water has a high heat capacity –
这意味着你可以将很多热量
that means that you can pump loads
泵入水中
of thermal energy into it
它的温度也只会升高一点点
and the temperature of the water will only rise a little bit –
这就是为什么电热水壶烧水需要这么多电能
it’s why electric kettles use so much power.
而且水也是一种非常好的热导体
And water’s a pretty good thermal conductor as well –
所以它也很擅长于从它周围的物体中吸收热量同时温度也不会变的很高
so it’s good at sucking the thermal energy from its surroundings without getting hot.
所以用水来点燃火柴
So it might seem surprising, then,
这看上去可能会很神奇
that you could light a match with water.
但是如果你能够让水
But of course if you got the water so hot,
变的比火焰还要热
that it was hotter than a flame, well,
那样的话水就不能从火焰中吸收热量了
it wouldn’t be able to suck thermal energy from the flame
因为这样热梯度的方向就错了 对吗？
because the thermal gradient would be in the wrong direction, right?
因为热量总是从高温物体传到低温物体
Because thermal energy flows from hot things to cold things.
所以事实证明你需要让水变的非常热
So it turns out that you need to get the water incredibly hot.
比如说超过水的沸点
Like hotter than the boiling point,
温度远比水的沸点还高的话 就会形成过热蒸汽
away hotter than the boiling point, so it’s superheated steam.
你要得到过热蒸汽首先要制作正常蒸汽
You can make superheated steam by first of all making normal steam ,
只要将水煮沸
so just boil the water,
然后将蒸汽通入一卷金属管中 并加热金属管
and then direct the steam through a coil, and then heat the coil.
那么从另一端出来的就是过热蒸汽了
What comes out the other end is superheated steam.
如果你能够让它足够热
If you can get it hot enough,
那么你就能用它点燃火柴了
you can set light to a match.
实际上 我是在几年前第一次看到Farrah Nazir做这个实验演示的
I first saw this demonstration done by Farrah Nazir, years ago, actually.
她在科学外延方面做得很棒
She does great stuff with science outreach –
她现在在维康信托基金会的公众参与部
she’s currently in the Public Engagement department
但你可以在网上查到她正在做得事情
at the Wellcome Trust, but you can check out what she’s doing online.
我发现一些很有趣的事情
Something I noticed that’s interesting is
那就是当你用火烧的时候
that the copper coil turns black
金属管会变黑
when you turn the flame on.
这些黑色的东西是氧化铜
The black stuff is actually copper oxide,
铜在空气中和氧气反应
so the copper has reacted with oxygen
而这个反应
in the air and that reaction is
会被高温加速
sped up by the high temperatures.
说它有趣是因为我认为氧化铜是绿色的原因
It’s interesting’cause I thought copper oxide was green –
和自由女神像是绿色的原因是一样的
like that’s why the Statue of Liberty is green:
铜在空气中和氧气反应
the copper has reacted with the oxygen in the air,
但实际上绿色物质是在下一阶段才出现的
but actually the green stuff is a later stage.
因此你先会得到氧化物
So you get oxidation first,
然后再和大气中的
and then you get a reaction with the carbon dioxide
二氧化碳和硫反应
in the atmosphere, and the sulfur as well.
这个和二氧化碳的反应
The reaction
生成了一种叫做孔雀石的绿色物质
with the carbon dioxide leads to a mineral called malachite and malachite is green –
这也就是自由女神像是绿色的原因
that’s why the Statue of Liberty is green,
但氧化铜自身是黑色物质
but the copper oxide on its own is the black stuff.
此视频由Squarespace赞助播出
This video is sponsored by Squarespace,
如你所知
as you know I’m working on a website
我在我爸的一个登载他关于自然与科学知识
with my dad to publish his articles about
的网站工作
science and the nature of knowledge,
因为我非常希望你们能够读到他们
’cause I really want you guys to be able to read them.
我们正通过Squarespace来实现
And we’re doing it
我刚把它交给我爸爸
through Squarespace. I’ve just handed it off to my dad –
他正在写这些方面的文章
he’s filling in all those articles,
我们使用的是内置在Squarespace中的博客系统
we’re using the blogging system that’s built into Squarespace.
超级简单的
Super easy.
这看起来很神奇
It looks amazing.
我们刚通过Squarespace购买了域名
We just bought our domain name through Squarespace as well
如果你想来看看 你可以登录howknowledgeworks.com
it’s howknowledgeworks.com you can visit it
但它是有密码保护的 因为它还没有准备好
if you want but it’s password-protected’cause it’s not ready for the big time yet,
你知道的我会弄好它的
but I will you know,
它有望在一周内上线届时我会告诉大家这个消息的
hopefully in a week or so it’ll be up and I will announce it.
总之 感谢Squarespace让做这件事变的如此简单
But yeah, thanks to Squarespace for making it super easy.
我还想告诉你
What else to tell you –
你可以在Squarespace上卖东西
You can sell stuff through Squarespace,
如果你想这么做的话它是有一个完整的商务系统的
so it’s got a whole ecommerce thing if you want to do that
这儿没有任何东西需要升级 修补或者安装
There’s never anything to upgrade or patch or install.
用起来真的非常简单
It’s really easy to use Yeah,
你今天就应该登录squarespace.com去免费试用一下
you should go to squarespace.com today
当你准备好启动你的项目时
for your free trial and when you’re ready to launch your project go
去squarespace.com/stevemould来获得首次购买的10%优惠
to squarespace.com/stevemould for 10% off your first purchase.
我希望你能喜欢这个视频
I hope you enjoyed this video, if
喜欢的话别忘了点击订阅哦
you did, don’t forget to hit subscribe,
下次再见
and I’ll see you next time.