評論
打印
Hi, I'm Jessica
嗨，我是Jessica
Today I'm gonna talk to you about a chemical demonstration I like to call
今天我要講的化學演示叫作
colorful indicators
多彩指示劑
Indicators show us what we normally wouldn't be able to see
指示劑/物能夠指示出我們一般看不到的情況
from the canary in the coal mine
包括煤礦地中的金絲雀
to a paint that changes color with temperature
隨溫度改變顏色的顏料
to the acid-base indicators we'll be seeing today
以及今天我們要看的酸堿指示劑
And chemist Dr. Bassam Shakhashiri
化學家Bassam Shakhashiri博士
here he is
這就是他了
is going to be showing us the demo
他將為我們進行演示
He's the president of the American Chemical Society
他是美國化學學會主席
and performing this demo right here at MIT
演示是在MIT這里進行的
You know, what I'm going to do is an experiment
下面我要做的實驗
using another form of carbon dioxide that's called dry ice
將用到另一種形式的二氧化碳，叫作干冰
Dry ice is solid carbon dioxide
干冰是固態二氧化碳
and you'll notice I'm putting what on?
看這里我戴上了什么
Putting gloves
帶上手套
And I'm going to open this bucket and pick up 3 chunks of carbon dioxide
我將打開這個桶，并取出三塊二氧化碳
Solid, this a solid carbon dioxide
這是固態二氧化碳
Its temperature is -78 degrees Celsius
其溫度是-78攝氏度
It's very cold
非常冰冷
Dry ice changes from being solid to a gas by a process we call...
干冰從固態變為氣態的過程叫作…
sublimation
升華
Sublimation is happening right now but we can't see it
升華正在發生，但我們看不到
how come we can't see it?
為什么看不到呢
Because carbon dioxide is gas. It's what?
因為二氧化碳是氣體，它是怎樣的
It's invisible. It has no color, so
它是無色透明的
sublimation is happening right now
升華正在發生
We can't see it
我們看不到
and I'm gonna put those three back in here
我將把這三個放回去
and ask you to focus your attention
然后讓你們把注意力
on what you see between my two hands here
集中到我兩手中間的這里
What do you see between my two hands?
我兩手中間是什么
In order to sharpen your powers of observation
為了增強你們的觀察能力
and develop the skills of reporting these observations
培養你們匯報觀察結果的能力
I ask you to pretend to be the play by play radio announcer
我將要求你們假裝自己是一名電臺解說員
describing to someone who's not with us what's going on
為沒有在場的人描述發生了什么
not a TV announcer
不是電視解說員
that person's got made because the picture tells almost everything
電視解說沒什么用，畢竟從圖像就能看清楚一切
So, there are how many cylinders?
這里有多少個柱形容器
And what do you see inside the cylinders?
柱形容器中能看到什么
Colored liquids. I'm listening to you on the radio
有色液體，我正在收音機前聽你們講
and what I hear you say is that there are six cylinders
我聽到你們說這里有六個柱形容器
and they have in them colored liquids
其中有各色液體
Come on
繼續
your brain learned a lot more information than those 2 statements, right?
你們腦海里知道的信息要遠遠多于這兩點
So they're about this big
它們大概有這么大
you said, but I can't see you on the radio saying it's about this big, right?
但我在收音機前看不到這么大是多大
You've got to do better than this
你們要給出更好的描述
Are they one hundred millimeters in size?
它們體積是100毫升嗎
Are they ten liters in size? Are there somewhere in between?
它們體積是10升嗎，還是在這之間
Yes, we put a bracket on it when we estimate a science, we put a bracket on it
對，我們進行科學估計時，會進行分段
Alright, and they have, yes, colored liquids
好，確實，這里有各色液體
How do you know they're liquids?
你們怎么知道是液體的
They could be jells. How can you find out?
它們也可以是膠狀物，你們怎么知道不是
We shake them up a little bit
我們可以搖一搖
because we know from experience, it's a keyword
根據經驗就知道了，經驗是個關鍵字
we learn things, our brain learns things, so we use them, right?
我們學到東西，大腦學到知識，我們使用它們
So they're liquids
這些是液體
So I'm going to take chunks of dry ice
我將取一些干冰
and put them into cylinders in a very special way
放到柱形容器內
and when I get done
完成之后
you tell me what the specialty is
你們要告訴我發生了什么
What's blowing out?
什么不斷冒出來
You see any bubbles?
看到泡泡了嗎
What kind of bubbles are those?
這些是什么泡泡
Well, do you wanna know what's in there?
想知道這其中是什么嗎
You already know what's in there, the dry ice, I put the dry ice in there
你們已經知道其中是什么了，干冰，我加入的是干冰
What did I put the dry ice into?
我把干冰加到什么中了
Into cylinders that have colored liquids in them, right?
放到裝有各色液體的柱形容器中
And I put the dry ice in every other cylinder
而且干冰被放入到每隔一個的柱形容器
I didn't put it in every cylinder, right?
而不是放到每個柱形容器中
Every other cylinder
每隔一個柱形容器
leaving one for comparison purposes, so
留一個作為對比
these are dyes that change color when the pH of the liquid changes
這些是染料，其顏色會隨液體pH值變化而變化
Alright, so let's break down what's happening in these cylinders
我們來分析一下柱形容器中發生的情況
There are 6 of them
總共有六個容器
and each set is a different color
每一組的顏色都不同
because they're different acid-base indicators inside them
因為每一組都是不同的酸堿指示劑
So this set starts out blue
這一組最開始是藍色的
This one starts out pink
這一組最開始是粉色的
And the final one is purple
最后一組則是紫色的
And every cylinder contains a few drops of sodium hydroxide
每一組柱形容器中都包含少許氫氧化鈉
which is a base
這是一種堿
NaOH, sodium hydroxide NaOH
氫氧化鈉
and it's a base
它是一種堿
