字幕列表 影片播放 列印所有字幕 列印翻譯字幕 列印英文字幕 What would you say 你說在過去幾世紀裡 is the most important discovery 什麼是人類最重要的發現？ made in the past few centuries? 是電腦？ Is it the computer? 汽車？ The car? 電力？ Electricity? 還是發現原子？ Or maybe the discovery of the atom? 我會說是這項化學反應： I would argue that it is this chemical reaction: 一個氮氣分子 a nitrogen gas molecule 加上三個氫氣分子 plus three hydrogen gas molecules 得到兩個氨氣分子 gets you two ammonia gas molecules. 這就是哈柏法 This is the Haber process 將空氣中的氮分子 of binding nitrogen molecules in the air 與氫分子結合 to hydrogen molecules, 或將空氣變成肥料 or turning air into fertilizer. 沒有這項反應 Without this reaction, 農夫僅可生產足夠 farmers would be capable of producing enough food 四十億人口所需的食物 for only 4 billion people; 我們目前的人口剛剛超過七十億 our current population is just over 7 billion people. 所以，沒有哈柏法 So, without the Haber process, 有超過三十億的人會沒食物吃 over 3 billion people would be without food. 你看，氮以硝酸鹽 NO3 的形式存在 You see, nitrogen in the form of nitrate, NO3, 是植物生存的一種基本營養素 is an essential nutrient for plants to survive. 當作物生長，他們消耗氮 As crops grow, they consume the nitrogen, 從土壤中吸收氮 removing it from the soil. 土壤中的氮可經由 The nitrogen can be replenished 長時間的自然施肥法補充 through long, natural fertilization processes 像動物腐化 like decaying animals, 但人類想以更快的方法 but humans want to grow food 種植糧食 much faster than that. 那麼，這就是令人沮喪的部分： Now, here's the frustrating part: 空氣的組成中有 78% 為氮 78% of the air is composed of nitrogen, 但作物不能從空氣直接利用氮 but crops can't just take nitrogen from the air 因為它含有非常強的三鍵 because it contains very strong triple bonds, 作物無法分解 which crops cannot break. 基本上哈柏所做的 What Haber did basically 是找出一種方法 was figure out a way 把空氣中的氮 to take this nitrogen in the air 放進土壤中 and put it into the ground. 1908 年，德國化學家弗里茨·哈柏 In 1908, the German chemist Fritz Haber 發展出一種化學方法 developed a chemical method 以利用空氣中取之不盡的氮 for utilizing the vast supply of nitrogen in the air. 哈柏發現一種方法 把空氣中的氮 Haber found a method 與氫氣鍵結 which took the nitrogen in the air 以形成氨 and bonded it to hydrogen 然後氨可被注入土壤中 to form ammonia. 在土裡快速轉變成硝酸鹽 Ammonia can then be injected into the soil, 但如果哈柏法要能拿來用在 where it is quickly converted into nitrate. 餵飽全世界 But if Haber's process was going to be used 他必須找出一種 能快速簡易製造出氨的方法 to feed the world, 為了瞭解 he would need to find a way 哈柏如何達成這項豐功偉業 to create a lot of this ammonia quickly and easily. 我們必須對 In order to understand 化學平衡有一番瞭解 how Haber accomplished this feat, 要達到化學平衡 we need to know something 你的化學反應要在封閉容器下進行 about chemical equilibrium. 舉例來說，你把 Chemical equilibrium can be achieved 氫氣及氮氣放在封閉容器內 when you have a reaction in a closed container. 讓它們反應 For example, let's say you put 實驗開始時 hydrogen and nitrogen into a closed container 我們有大量的氮及氫 and allow them to react. 所以氨的形成 In the beginning of the experiment, 以高速進行 we have a lot of nitrogen and hydrogen, 但當氫及氮反應一段時間 so the formation of ammonia 到快用完的時候 proceeds at a high speed. 反應變慢 But as the hydrogen and nitrogen react 因為瓶子裡的氮及氫變少了 and get used up, 最終，氨分子會達到一種情況 the reaction slows down 就是它們又開始分解 because there is less nitrogen and hydrogen 成為氮氣及氫氣 in the container. 一段時間後，這兩種反應 Eventually, the ammonia molecules reach a point 就是產生及分解氨氣 where they start to decompose 會達到相同速率 back into the nitrogen and hydrogen. 當這兩個速率相等時 After a while, the two reactions, 我們就說反應達到平衡 creating and breaking down ammonia, 這聽起來不錯，但並非如此 will reach the same speed. 尤其當你只想要 When these speeds are equal, 產生一噸的氨氣時 we say the reaction has reached equilibrium. 哈柏根本不想讓氨氣 This might sound good, but it's not 再分解回去 when what you want 但如果你就是把這項反應 is to just create a ton of ammonia. 放在封閉容器裡進行 Haber doesn't want the ammonia 那就是必然的結果 to break down at all, 這也就是亨利·路易·勒夏特列 but if you simply leave the reaction 這位法國化學家 in a closed container, 可以幫忙的地方 that's what will happen. 他發現 Here's where Henry Le Chatelier, 如果你把達到反應平衡的系統 a French chemist, 加入某項東西 can help. 像是，這麼說，氮氣 What he found was 這個系統會持續進行 that if you take a system in equilibrium 直到再達到平衡為止 and you add something to it, 勒夏特列同時發現 like, say, nitrogen, 如果你增加 the system will work 一個系統的壓力 to get back to equilibrium again. 這個系統會試著 Le Chatelier also found 回到原有的壓力 that if you increase 這就像身處擁擠的房間 the amount of pressure on a system, 分子愈多 the system tries to work 壓力愈大 to return to the pressure it had. 如果我們回頭去看我們的方程式 It's like being in a crowded room. 我們會看見在左邊 The more molecules there are, 左邊有四個分子 the more pressure there is. 而右邊只有兩個 If we look back at our equation, 所以，如果我們想讓房間不那麼擠 we see that on the left-hand side, 並因而產生較小的壓力 there are four molecules on the left 這個系統就會開始 and just two on the right. 結合氮及氫 So, if we want the room to be less crowded, 製造出較小巧緊密的氨分子 and therefore have less pressure, 哈柏瞭解到為了製造 the system will start 大量的氨 combining nitrogen and hydrogen 他必須發明一種機器 to make the more compact ammonia molecules. 可以持續加入氮及氫 Haber realized that in order to make 同時也要增加壓力 large amounts of ammonia, 在這平衡系統上 he would have to create a machine 這也正是他所做的 that would continually add nitrogen and hydrogen 今天，氨是世上產量最多的 while also increasing the pressure 化學化合物之一 on the equilibrium system, 每年產量粗估為 1 .31 億公噸 which is exactly what he did. 亦即二千九百億磅的氨 Today, ammonia is one of the most produced 這是大約 chemical compounds in the world. 三千萬隻非洲象的總重 Roughly 131 million metric tons are produced a year, 每頭約以一萬磅來算 which is about 290 billion pounds of ammonia. 80% 生產出的氨拿來做肥料 That's about the mass 其餘則使用在 of 30 million African elephants, 工業及家用清潔用品上 weighing roughly 10,000 pounds each. 並拿來生產其他種氮化合物 80% of this ammonia is used in fertilizer production, 譬如硝酸 while the rest is used 最近的研究發現 in industrial and household cleaners 半數肥料中的氮 and to produce other nitrogen compounds, 沒有被植物同化 such as nitric acid. 結果是，氮就以 Recent studies have found 揮發性化學化合物的形式 that half of the nitrogen from these fertilizers 在地球的供水及大氣中被發現 is not assimilated by plants. 嚴重破壞我們的環境 Consequently, the nitrogen is found 當然，在哈柏發表他的發明時 as a volatile chemical compound 無法預測這個問題 in the Earth's water supplies and atmosphere, 為了承接他的開創視野 severely damaging our environment. 當代科學家正在尋找 Of course, Haber did not foresee this problem 21 世紀的新哈柏法 when he introduced his invention. 以達到同樣程度的幫助 Following his pioneering vision, 卻無危險的後果 scientists today are looking for a new Haber process of the 21st century, which will reach the same level of aid without the dangerous consequences.