Hi, I'm Jessica

嗨，我是Jessica

Today I'm gonna talk to you about a chemical demonstration I like to call

今天我要讲的化学演示叫作

colorful indicators

多彩指示剂

Indicators show us what we normally wouldn't be able to see

指示剂/物能够指示出我们一般看不到的情况

from the canary in the coal mine

包括煤矿地中的金丝雀

to a paint that changes color with temperature

随温度改变颜色的颜料

to the acid-base indicators we'll be seeing today

以及今天我们要看的酸碱指示剂

And chemist Dr. Bassam Shakhashiri

化学家Bassam Shakhashiri博士

here he is

这就是他了

is going to be showing us the demo

他将为我们进行演示

He's the president of the American Chemical Society

他是美国化学学会主席

and performing this demo right here at MIT

演示是在MIT这里进行的

You know, what I'm going to do is an experiment

下面我要做的实验

using another form of carbon dioxide that's called dry ice

将用到另一种形式的二氧化碳，叫作干冰

Dry ice is solid carbon dioxide

干冰是固态二氧化碳

and you'll notice I'm putting what on?

看这里我戴上了什么

Putting gloves

带上手套

And I'm going to open this bucket and pick up 3 chunks of carbon dioxide

我将打开这个桶，并取出三块二氧化碳

Solid, this a solid carbon dioxide

这是固态二氧化碳

Its temperature is -78 degrees Celsius

其温度是-78摄氏度

It's very cold

非常冰冷

Dry ice changes from being solid to a gas by a process we call...

干冰从固态变为气态的过程叫作…

sublimation

升华

Sublimation is happening right now but we can't see it

升华正在发生，但我们看不到

how come we can't see it?

为什么看不到呢

Because carbon dioxide is gas. It's what?

因为二氧化碳是气体，它是怎样的