評論
打印
Hi, I'm Jessic
嗨 我是Jessica
And today, I'm going to be talking about a chemical demonstration
今天我要講的化學演示
I like to call "Money to Burn"
叫作"燒錢"
and chemist Dr. Bassam Shakhashir
化學家Bassam Shakhashiri博士
here he is
這就是他
is actually going to be showing us the dem
將為我們進行這個演示
He's the president of the American Chemical Societ
他是美國化學學會主席
and is performing this demo right here at MIT
他在我們MIT進行了這個演示
Let's see if he has some money to bur
看看他是怎么燒錢的
What I'm going to do now i
下面我將
I'm going to reach in here, I'm going to take a dollar bil
從錢包里拿出一張美鈔
and I'm going to put it into flame just like that
像這樣把它放到火焰里
Was that too fast?
這是否太快了
What we always do in science is repeat the experiment
在科學里 我們總喜歡重復實驗
So I think although it looks like a dollar bill
它雖然看起來像美鈔
it's not a real dollar bill
但不是真正的美鈔
I bring it close to the flame
我讓它靠近火焰
It disappears into thin air. It looks like magic, right?
它瞬間消失掉了 這很像魔術(shù) 不是嗎
I love magi
我很愛魔術(shù)
Magic is engaging
魔術(shù)很迷人
but not informativ
但說明不了問題
How is that dollar bill burning up so quickly?
那張美鈔是如何快速燃燒掉的
Well, it's actually not a dollar bil
實際上 它不是一張美鈔
It's called flash pape
而是一張閃光紙
And it's paper that has been treated with chemical
這種紙用化學藥劑處理過
to make it burn quickly and leave no ashes
讓它能夠快速燃燒 而且不留灰燼
Now flash paper has been nitrate
閃光紙被硝化過
Practically what that means is tha
實際也就是
you soak the paper in a mixture of concentrated nitric and sulfuric acid
將紙張浸入到濃的硝酸硫酸混合物中
The cellulose in the paper then reacts with the aci
紙張中的纖維素會同酸反應
to produce nitrated cellulose and wate
生成硝化纖維素和水
The reaction is this
反應是這樣的
So our nitric acid her
這是硝酸
mixes with the cellulose
同纖維素反應
Now this is actually just one unit in the big polymer that is cellulos
這其實只是纖維素大聚合物中的一個單元
It's got lots of little units of C6H10O5
纖維素包括很多單元
So in this equation, I'm only writing one unit
而這個方程中 我只寫了一個單元
And that's creating nitrated cellulose and wate
這會生成硝化纖維素和水
Now the nitro group, the NO2, is the reactive grou
硝基NO2是活性基團
and it can be very reactive depending on the molecule that it's in
在有些分子中時 它的活性會非常高
You've no doubt heard of nitroglycerin
你們肯定聽說過硝酸甘油
which looks like thi
它是這樣的
It's an explosive liquid
它是一種爆炸性液體
Or TNT
還有TNT
which actually stands for trinitrotoluene
全稱是三硝基甲苯
It looks like thi
它是這樣的
So all of these molecules have nitro group in them
所有這些分子中都有硝基
And it's the nitro or NO2 groups that make these molecules explosiv
正是硝基NO2讓這些分子具有爆炸性
Now let's watch what happens when Dr. Shakhashiri tries this again
下面再來看Shakhashiri博士的第二次嘗試
but this time with a real dollar bil
不過這次 他將用到真正的美鈔
I'd like someone in the audience to
我想問某位觀眾
let me borrow from them a real one dollar bill
借一張真正的一美元鈔票
Is there someone in the audience who would let me
在座各位誰愿意
who would trust me with a real one dollar bill?
借一張一美元鈔票給我嗎
Or a five-dollar bill
五美元鈔票也行
Steve, how about a twenty-dollar bill, ha? Steve
有二十美元鈔票嗎
You've got a twenty-dollar bill?
有二十美元鈔票嗎
Okay, here's one-dollar bill
好的 一美元鈔票
It's a real one dolla
貨真價實
but you don't know what I'm going to do with it, don't you?
你不知道我會拿它做什么
