The chemical reaction that feeds the world - Daniel D. Dulek

养活世界的化学反应—Daniel D. Dulek

翻译人员: Ying Minako Zhao 校对人员: Yixuan Liu

What would you say

对你来说

is the most important discovery

在过去几个世纪里

made in the past few centuries?

人类最重大的发现是什么？

Is it the computer?

电脑？

The car?

汽车？

Electricity?

电？

Or maybe the discovery of the atom?

还是原子的发现？

I would argue that it is this chemical reaction:

我认为应该是以下的化学反应：

a nitrogen gas molecule

一个氮气分子

plus three hydrogen gas molecules

加上三个氢气分子

gets you two ammonia gas molecules.

反应产生两个氨气分子

This is the Haber process

这个叫做哈伯制氨法

of binding nitrogen molecules in the air

它将空气中的氮气分子

to hydrogen molecules,

与氢气分子结合

or turning air into fertilizer.

将空气变为肥料

Without this reaction,

如果没有哈伯制氨法

farmers would be capable of producing enough food

那么全世界的粮食产量

for only 4 billion people;

最多只能养活40亿人

our current population is just over 7 billion people.

而我们现在的世界人口超过70亿

So, without the Haber process,

所以，如果没有哈伯制氨法

over 3 billion people would be without food.

超过30亿人将没有食物

You see, nitrogen in the form of nitrate, NO3,

硝酸盐（NO3）中的氮元素

is an essential nutrient for plants to survive.

是植物生长所必需的营养

As crops grow, they consume the nitrogen,

农作物在生长时

removing it from the soil.

从土壤中吸收氮

The nitrogen can be replenished

通过自然的方式

through long, natural fertilization processes

来补充土壤中的氮则需要很长时间

like decaying animals,

比如从动物尸体的腐烂过程中产生。

but humans want to grow food

但是人们往往需要在更短时间内耕种农作物

much faster than that.

但是人们往往需要在更短时间内耕种农作物

Now, here's the frustrating part:

让大家特别头疼的是：

78% of the air is composed of nitrogen,

虽然氮气占空气成分的78%

but crops can't just take nitrogen from the air

但是农作物不能直接从空气中吸收氮气

because it contains very strong triple bonds,

因为氮气分子拥有坚固的三键结构

which crops cannot break.

很难被农作物破坏

What Haber did basically

哈伯找到了一种

was figure out a way

能够把空气里的氮吸取出来

to take this nitrogen in the air

然后注入土壤中的方法

and put it into the ground.

然后注入土壤中的方法

In 1908, the German chemist Fritz Haber

在1908年，德国化学家弗里茨·哈伯

developed a chemical method

发明了一种化学方法

for utilizing the vast supply of nitrogen in the air.

有效地将空气中丰富的氮资源利用起来

Haber found a method

which took the nitrogen in the air

他的这种方法

把空气中的氮气与氢气结合

and bonded it to hydrogen

把空气中的氮气与氢气结合

to form ammonia.

形成氨气

Ammonia can then be injected into the soil,

氨气可以被注入土壤中

where it is quickly converted into nitrate.

并且很快地被转化成硝酸盐

But if Haber's process was going to be used

但是如果要用哈伯制氨法

to feed the world,

来保证世界粮食产量

he would need to find a way

他则须要找到一种能够快速且容易的制造氨气的方法

to create a lot of this ammonia quickly and easily.

他则须要找到一种能够快速且容易的制造氨气的方法

In order to understand

为了理解

how Haber accomplished this feat,

哈伯是怎样完成此壮举的

we need to know something

我们首先需要了解一些关于化学平衡的知识

about chemical equilibrium.

我们首先需要了解一些关于化学平衡的知识

Chemical equilibrium can be achieved

化学平衡可以在密封容器里进行反应时被达到

when you have a reaction in a closed container.

化学平衡可以在密封容器里进行反应时被达到

For example, let's say you put

例如

hydrogen and nitrogen into a closed container

你把氢气和氮气放入密封容器中

and allow them to react.

让它们进行反应

In the beginning of the experiment,

在实验刚刚开始的时候

we have a lot of nitrogen and hydrogen,

我们有许多的氮气和氢气

so the formation of ammonia

它们高速地发生反应

proceeds at a high speed.

形成氨气

But as the hydrogen and nitrogen react

但是，持续的反应渐渐消耗氢气和氮气

and get used up,

但是，持续的反应渐渐消耗氢气和氮气

the reaction slows down

因为容器中

because there is less nitrogen and hydrogen

氢气和氮气的量减少

in the container.

反应速度随之减慢

Eventually, the ammonia molecules reach a point

最终，氨气分子到达一个临界点

where they start to decompose

它们开始分解成氮气和氢气

back into the nitrogen and hydrogen.

它们开始分解成氮气和氢气

After a while, the two reactions,

此后，两种化学反应

creating and breaking down ammonia,

即氨气的形成和分解

will reach the same speed.

将渐渐达到同样的速度

When these speeds are equal,

当它们等速时

we say the reaction has reached equilibrium.

反应便被称为达到了化学平衡

This might sound good, but it's not

这听起来不错，但其实不然

when what you want

因为你仅仅是想制造一吨纯的氨气

is to just create a ton of ammonia.

因为你仅仅是想制造一吨纯的氨气

Haber doesn't want the ammonia

哈伯不想让反应产生的氨气分解

to break down at all,

哈伯不想让反应产生的氨气分解

but if you simply leave the reaction

但如果让此化学反应在密封容器中自由进行

in a closed container,

但如果让此化学反应在密封容器中自由进行

that's what will happen.

氨气便会分解

Here's where Henry Le Chatelier,

法国化学家

a French chemist,

亨利·路易·勒夏特列

can help.

帮上了忙

What he found was

他发现

that if you take a system in equilibrium

如果你向已达到化学平衡的系统里

and you add something to it,

加上一些东西

like, say, nitrogen,

比如，氮气

the system will work

那么这个系统会自动调整，以重新回到平衡

to get back to equilibrium again.

那么这个系统会自动调整，以重新回到平衡

Le Chatelier also found

勒夏特列还发现

that if you increase

如果增大系统的压力

the amount of pressure on a system,

如果增大系统的压力

the system tries to work

为了返回到以前的压力状态，系统将继续反应

to return to the pressure it had.

为了返回到以前的压力状态，系统将继续反应

It's like being in a crowded room.

就像在一个拥挤的房间

The more molecules there are,

分子的数量越多

the more pressure there is.

系统的压力就越大

If we look back at our equation,

让我们看看这个反应的化学方程式

we see that on the left-hand side,

在方程式的左边有四个分子

there are four molecules on the left

在方程式的左边有四个分子

and just two on the right.

而方程式的右边只有两个分子

So, if we want the room to be less crowded,

所以，为了让房间变得不那么拥挤

and therefore have less pressure,

以至减小压力

the system will start

氮气和氢气的合成反应会重新开始

combining nitrogen and hydrogen

氮气和氢气的合成反应会重新开始

to make the more compact ammonia molecules.

产生更加小巧的氨气分子

Haber realized that in order to make

哈伯意识到为了制造大量的氨气

large amounts of ammonia,

哈伯意识到为了制造大量的氨气

he would have to create a machine

他必须首先创造一台机器

that would continually add nitrogen and hydrogen

可以连续不断地注入氢气和氮气

while also increasing the pressure

并且持续增加平衡系统的压力

on the equilibrium system,

并且持续增加平衡系统的压力

which is exactly what he did.

他做到了

Today, ammonia is one of the most produced

今天，氨气是世界上被制造得

chemical compounds in the world.

最多的化合物之一

Roughly 131 million metric tons are produced a year,

每年大约有1亿3千1百万公吨的氨气被产出

which is about 290 billion pounds of ammonia.

重量大约为2900亿磅

That's about the mass

这个相当于

of 30 million African elephants,

3千万头每头约1万磅重的非洲大象的总重

weighing roughly 10,000 pounds each.

3千万头每头约1万磅重的非洲大象的总重

80% of this ammonia is used in fertilizer production,

80%的氨气被用于制造肥料

while the rest is used

剩下的20%被用于

in industrial and household cleaners

工业和家庭用的清洁剂中

and to produce other nitrogen compounds,

以及制造其它氮化物

such as nitric acid.

例如，硝酸

Recent studies have found

最近的研究显示

that half of the nitrogen from these fertilizers

化肥中一半的氮都没有被植物吸收

is not assimilated by plants.

化肥中一半的氮都没有被植物吸收

Consequently, the nitrogen is found

之后，我们发现氮是具挥发性的化合物

as a volatile chemical compound

之后，我们发现氮是具挥发性的化合物

in the Earth's water supplies and atmosphere,

积存在地球的水和大气中

severely damaging our environment.

对我们的环境造成极大污染

Of course, Haber did not foresee this problem

当然，在哈伯发明制氮法时

when he introduced his invention.

他并没有预见到这个问题

Following his pioneering vision,

继承哈伯的开创性的发明

scientists today are looking

今日的科学家们在找寻一种21世纪的新制氮法

for a new Haber process of the 21st century,

今日的科学家们在找寻一种21世纪的新制氮法

which will reach the same level of aid

它既可以达到制氮的目的

without the dangerous consequences.

又不会给人类带来不好的后果