The strengths and weaknesses of acids and bases - George Zaidan and Charles Morton

酸和堿的強與弱 - George Zaidan 與 Charles Morton

1,024,008 views

2013-10-24 ・ TED-Ed


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The strengths and weaknesses of acids and bases - George Zaidan and Charles Morton

酸和堿的強與弱 - George Zaidan 與 Charles Morton

1,024,008 views ・ 2013-10-24

TED-Ed


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譯者: XIN YUE 審譯者: Bighead Ge
00:06
Acids and bases are everywhere.
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酸與堿無處不在。
00:08
They're used to make foods,
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它們被用來製作食物,
00:10
soaps and detergents,
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香皂和清潔劑,
00:11
fertilizers,
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化肥,
00:12
explosives,
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炸藥,
00:13
dyes,
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染料,
00:14
plastics,
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00:14
pesticides,
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塑膠,
農藥,
00:15
even paper.
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還有紙。
00:16
Our stomachs are very acidic.
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我們的胃裡是強酸性的。
00:18
Our blood is slightly basic.
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我們的血液是呈弱鹼的。
00:20
Our proteins are made up of amino acids,
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我們的蛋白質是由氨基酸組成的,
00:22
and the letters in our genetic code,
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還有那些遺傳密碼中的字母,
00:24
those As, Ts, Cs, and Gs,
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As,Ts, Cs, 和 Gs,
00:26
are all bases.
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都是堿。
00:28
You were probably taught
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你可能學過
00:29
how acids and bases behave
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分子級的酸和堿
00:30
on the molecular level.
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如何作用。
00:32
You were probably never taught
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你可能從不知道
00:34
that a long time ago,
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很久以前,
00:35
like ancient Greek ago,
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比古希臘還往前,
00:37
before anyone knew about atoms or molecules,
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在沒有人知道原子或分子時,
00:39
acids and bases were defined
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酸和堿已經因它們的
00:41
by how they behaved.
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作用表現而有定義。
00:43
Acids tasted sour and corroded metal.
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酸嘗起來是酸的,還腐蝕金屬。
00:46
Bases felt slippery
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堿觸感滑
00:48
and could somehow counteract acids.
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還能一定程度上抵消酸的作用。
00:52
When molecules dissolved in water interact,
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當在水中溶解的分子相互作用,
00:54
they are exchanging two main currencies
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它們與周圍的物質交換
00:56
with their surroundings:
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兩個主要流通物
00:58
protons, also known as hydrogen ions,
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質子,也就是氫離子,
01:01
and electrons.
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以及電子。
01:02
Depending on how a molecule is composed or shaped,
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取決於分子的組成和形狀,
01:05
it may be willing to donate or accept
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在這個群體中,它與其他的成員之間
01:07
either protons or electrons
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可能願意釋放,或者接受
01:09
with some other community member.
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質子或電子。
01:11
And some molecules are far more aggressive than others
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有些分子在釋放或接受任一流通物時
01:14
when it comes to donating or accepting either currency.
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比其他分子強悍許多。
01:17
Remember that protons are positively charged
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切記質子是帶正電荷的
01:19
and electrons are negatively charged.
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電子是帶負電荷的。
01:22
So, if a molecule is willing to give up a proton,
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所以,如果一個分子要釋放一個質子,
01:24
that's not too different
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和接收一個電子
01:26
from it being willing to accept an electron --
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不會有什麼大的差異
01:28
either way it's becoming more negatively charged.
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任何一種方式都只會讓它帶更多負電荷。
01:31
Other molecules are willing to accept a proton
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其它分子想要接收質子
01:34
or give up an electron.
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或釋放一個電子。
01:36
These are becoming more positively charged.
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這些就變得帶有更多正電荷。
01:38
Some substances are so aggressive
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一些物質在釋放它們的質子時
01:41
about donating their protons
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表現得十分強勢,
01:42
that when they get a chance,
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一旦得到機會,
01:43
all of the molecules in a sample
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樣本中所有的分子都會
01:45
will dump a proton,
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釋放出一個質子,
01:46
sometimes more than one,
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有時是多個
01:48
to the surrounding water molecules.
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至周圍的水分子中。
01:50
We call these strong acids.
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我們稱這些為強酸。
01:53
Meanwhile, some compounds are so ready
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同時,一些化合物迫不及待
01:54
to accept a proton
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需要一個質子,
01:56
that they won't wait around,
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它們不會傻等,
01:57
they'll just rip one off water,
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而是直接從有兩個質子的水分子
01:59
which usually has two protons
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中搶一個過來,
02:00
but is generous enough to hang out with just one.
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但水分子很大方,剩一個質子也行。
02:03
We call these strong bases.
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我們把這些叫做強鹼。
02:05
Other acids and bases are not so strong.
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其它的酸和堿沒有那麼強。
02:08
They may donate just a few of their protons to water
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它們可以往水中釋放少量質子
02:11
or accept just a few protons from water,
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或從水中接受少量質子,
02:13
but most of their molecules stay exactly the same.
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但是它們的大多數分子都保持不變。
02:16
If left alone in water,
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如果被單獨置於水中,
02:18
they'll reach some equilibrium point
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在百分之一或
02:20
where maybe only one out of a hundred
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萬分之一的分子
02:22
or one out of ten thousand of their molecules
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與水交互流通時
02:23
has exchanged currency with water.
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達到某個平衡點
02:26
As you might guess,
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你可能猜測,
02:27
we label these acids and bases weak,
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我們把這些酸和堿標記為做弱酸,弱鹼,
02:30
but in the common sense of the word,
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但是常識中,
02:31
they're not weak.
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它們不弱。
02:32
The vinegar in your salad dressing
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你的沙拉調味的醋
02:34
that you can smell from across the room,
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的味道你能在整個房間裡聞到,
02:36
that is a weak acid.
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它是弱酸。
02:38
The ammonia you spray on glass
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氨水噴在玻璃上
02:39
for a streak-free shine,
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讓玻璃晶瑩剔透,
02:40
that is a weak base.
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那是弱鹼。
02:42
So, it doesn't take much to be an active player
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所以,在化學的經濟體系裡,
02:45
in the chemical economy.
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不必投入太多也能成為活躍玩家。
02:47
Most acid-base chemistry takes place in water,
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大多數的酸鹼化學過程都發生在水中,
02:50
which can act as either an acid or a base,
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水像一個24小時分子ATM,
02:53
accepting deposits and enabling withdrawals
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通過”吸納存款“和”授權取款“
02:54
like a 24-hour molecular ATM.
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起到酸或堿的作用。
02:57
And when a proton-deposit customer,
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但一個客戶存入質子,
03:00
that's an acid,
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它就是酸,
03:01
and a proton-withdrawal customer,
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當一個客戶提取質子,
03:03
the base,
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它是堿,
03:04
shop at the same time,
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當他們同時購物
03:05
their net effect on water's account
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他們在水中的有效效應
03:07
may cancel out,
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會抵消,
03:09
and we call this neutralization.
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我們把這個叫做中和作用。
03:11
Now, certain molecules can behave
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現在,一些分子不必融水
03:13
as acids or bases without water,
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就可以起到酸和堿的作用,
03:15
but that's another story.
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但那就是另一回事了。
03:17
Let's end by saluting water
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最後,我們向水致敬
03:19
as the resilient and fair banker
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因為它平衡酸和堿
03:20
for acids and bases.
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公平的銀行家。
03:22
It's always open for business,
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它總對商家開放,
03:24
doesn't charge interest,
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也不收利息,
03:25
and will never foreclose on your molecules,
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並且永遠不會阻止你贖回你的分子,
03:27
which is more than I can say for [bleep].
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酷斃了。
03:30
Waah-waah.
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哇-哇
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