How big is a mole? (Not the animal, the other one.) - Daniel Dulek

一莫耳有多大？(不是动物，也不是另外那一个）- Daniel Dulek

翻译人员: Minji Seo 校对人员: Ying Wang (王莹)

OK，今天我们来谈一下 'MOLE' （一字多义：莫耳、鼹鼠、痣）

OK, today we're going to talk about the mole.

我知道你在想什么,我知道什么是鼹鼠，

Now, I know what you're thinking: "I know what a mole is,

牠是一种在地下挖洞，摧毁花园的小毛绒绒生物

it's a small furry creature that digs holes in the ground and destroys gardens."

有些人也许会认为是在阿姨脸上，并带有几根细毛的痣

And some of you might be thinking that it's a growth on your aunt's face with hairs sticking out of it.

但今天所讲的莫耳， 是化学中的一个概念，用来计算分子、

Well, in this case, a mole is a concept that we use in chemistry to count molecules,

原子、或是任何极小物质的数量

atoms, just about anything extremely small.

你曾经想过这个宇宙到底有多少的原子吗？

Have you ever wondered how many atoms there are in the universe?

或是你的身体里？或是在一粒沙子里？

Or in your body? Or even in a grain of sand?

科学家想解开这个问题，

Scientists have wanted to answer that question,

但是你要如何计算小到像原子的东西？

but how do you count something as small as an atom?

在1811年，有个人突发奇想， 认为如果你有相同体积

Well, in 1811, someone had an idea that if you had equal volumes

的气体，在相同的温度及压力下，

of gases, at the same temperature and pressure,

它们应该会有相同的分子数量

they would contain an equal number of particles.

他的名字是 Lorenzo Romano Amedeo Carlo Avogadro （亚佛加厥）

His name was Lorenzo Romano Amedeo Carlo Avogadro.

我怀疑他要花多久时间签名

I wonder how long it took him to sign autographs.

不幸的是，大部份的科学家不接受这个想法，

Unfortunately for Avogadro, most scientists didn't accept the idea of the atom,

而他也没有方法可以证明他是对的

and there was no way to prove he was right.

原子和分子之间并没有明显的差异

There was no clear difference between atoms and molecules.

大多数的科学家认为 亚佛加厥的理论纯綷是个假说，

Most scientists looked at Avogadro's work as purely hypothetical,

并没有特别去思考这件事

and didn't give it much thought.

但事实证明他是对的 ! 1860年底，

But it turned out he was right! By late 1860,

亚佛加厥的想法被证明是对的， 而且他的努力奠定了

Avogadro was proven correct, and his work helped lay the foundation

原子理论的基石。不幸的是，亚佛加厥死于1856年

for the atomic theory. Unfortunately, Avogadro died in 1856.

问题是，即使是小东西上的分子总数也是

Now the thing is that the amount of particles in even small samples

非常巨大的。

is tremendous. For example,

假使你有一个汽球，装进任一种气体， 在摄氏零度

If you have a balloon of any gas at zero degrees Celcius,

和一大气压的条件下，那你会有刚刚好

and at a pressure of one atmosphere, then you have precisely

602乘10的21次方个气体分子

six hundred and two sextillion gas particles.

就是6后面带有 23 个0， 这么多个分子在里面

That is, you have six with 23 zeros after it particles of gas in the container.

或用科学记号表示为 6.02 × 10 23 个分子

Or in scientific notation, 6.02 times 10 to the 23rd particles.

这个例子有点误导人，

This example is a little misleading,

因为高动能的气体分子会占用较大的空间，

because gases take up a lot of space due to the high kinetic energy

这让你感觉原子比实际大小的还要大

of the gas particles, and it leaves you thinking atoms are bigger than they really are.

相对地，我们看一下水分子

Instead, think of water molecules.

如果你倒入 18.01 公克的水到杯子里，

If you pour 18.01 grams of water into a glass,

就是 18.01 毫升，大约是三个半茶匙的水，

which is 18.01 milliliters, which is like three and a half teaspoons of water,

你就有 6.02 × 10 23 个水分子

you'll have 602 sextillion molecules of water.

自从 Lorenzo Romano......嗯，算了。 亚佛加厥是第一位提出这个想法的人，

Since Lorenzo Romano - uh, never mind - Avogadro was the first one to come up with this idea,

科学家用他的名字来命名 6.02 × 10 23 这个数字

scientists named the number 6.02 times 10 to the 23rd after him.

这就是熟知的亚佛加厥常数

It is simply known as Avogadros's number.

现在，回到莫耳。不是在说鼹鼠

Now, back to the mole. Not that mole.

这个莫耳。没错，这个常数有另一个名字

This mole. Yep, this number has a second name.

莫耳，化学家使用莫耳这个术语

The mole. Chemists use the term mole

来表示 6.02 × 10 23 这个数量

to refer to the quantities that are at the magnitude of 602 sextillion.

就是大家知道的莫耳常数

This is known as a molar quantity.

原子和分子太小了，所以化学家将它们分成一群一群， 每一群就叫做一莫耳

Atoms and molecules are so small, that chemists have bundled them into groups called moles.

莫耳对于学生是很难了解的，因为他们很难想象

Moles are hard for students to understand because they have a hard time

1 莫耳的数量，

picturing the size of a mole,

或是 6.02 × 10 23

or of 602 sextillion.

它实在大到大脑难以理解

It's just too big to wrap our brains around.

记得刚刚说的 18.01 毫升的水吗？

Remember our 18.01 milliliters of water?

那就是 1 莫耳的水

Well, that's a mole of water.

但是这有多少？

But how much is that?

6.02 × 10 23 看起来像什么？

Exactly what does 602 sextillion look like?

也许这有帮助

Maybe this'll help.

用甜甜圈来代替水分子

Exchange the water particles for donuts.

假如你有 1 莫耳的甜甜圈，它们可以覆盖整个地球表面

If you had a mole of donuts, they would cover the entire earth

到 8 公里高，

to a depth of eight kilometers,

大约是 5 英哩

which is about five miles.

你需要很多咖啡来配

You really need a lot of coffee for that.

如果你有 1 莫耳的篮球，你可以制造和地球

If you had a mole of basketballs, you could create a new planet

一样大的星球

the size of the earth.

如果你一出生时，你有 1 莫耳的钱，你每一秒花一百万

If you received a mole of pennies on the day you were born and spent a million dollars

直到 100 岁你死的那一天，你还有 99.99% 以上

a second until the day you died at the age of 100, you would still have more than 99.99%

的钱在银行里。

of your money in the bank.

好了，现在我们大概对 1 莫耳有个概念了

OK. Now we sort of have an idea how large the mole is.

我们如何用它？

So how do we use it?

你也许会惊讶化学家使用它的方法，

You might be surprised to know that chemists use it the same way

就如同你用‘磅’来买葡萄，熟食肉类，或鸡蛋

you use pounds to buy grapes, deli meat, or eggs.

当你到杂货店时，你不会走到柜台

When you go to the grocery store, you don't go to the deli counter

要 43 片腊肠，你会买几磅的腊肠

and ask for 43 slices of salami, you buy your salami by the pound.

当你买鸡蛋时，你会买一打鸡蛋

When you buy your eggs, you buy a dozen eggs.

当我们听到‘打’这个字，我们会想到数字 12

When we hear the word dozen, we probably think of the number 12.

我们也知道一双就是 2，

We also know that a pair is two,

面包师父的一打是 13，

a baker's dozen is 13,

一箩是 144，一令纸......谁知道？

a gross is 144, and a ream of paper is - anybody?

一令纸是 500 张

A ream is 500.

一莫耳也是一样的

Well, a mole is really the same thing.

对化学家而言，1 莫耳就是 6.02 乘以10的23次方

For a chemist, a mole conjures up the number 6.02 times 10 to the 23rd,

而不是毛绒绒的动物。唯一的差别是

not a fuzzy little animal. The only difference is

我们比较熟悉其他的计数单位

that the other quantities are more familiar to us.

现在你知道了- 莫耳的故事

So there you have it - the story of the mole,

Avogadro, basketballs, and how to buy salami at the grocery store.