麻省理工公开课:魔术背后的化学(MP3+视频+中英字幕) 第8期:魔镜魔镜(2)
日期:2015-01-07 13:52

(单词翻译:单击)

视频文本

I don't think you see anything happening to you
现在应该还没发生
I'm still working on it
我还在努力
I'm getting tired here
我有点累了
Something happening?
发生了什么吗
Oh, my goodness, I could see myself
哦,我的天,我可以看到我自己了
Well, this is a real workout, I'll tell you
这个真的是太费体力了
So what we've created here is a beautiful silver mirrored flask
这里我们做成了一个银镜烧瓶
So look at that
看这个
Dr. Dolhun has created a beautiful silver mirror
Dolhun博士做成了一个漂亮的银镜
It almost looks like a Christmas tree ornament
就像是圣诞树上的装饰品一样
and a silver ornament could in fact be made this way
银色装饰确实也可以这样做
So here's what's happening
这里情况是这样的
Electrons from here, the glucose
电子来自葡萄糖
get transferred to the silver reducing it to silver 0
被转移给银离子,将其还原为Ag?
Silver 0 is insoluble in water. It's just silver metal Ag?
不溶于水,也就是银金属
And it's precipitating out on the inside of the flask
它会沉淀到烧瓶内面
forming the beautiful silver mirror that we see
形成我们所看到的漂亮银镜
Now this process is called reduction
这个过程叫作还原
And whenever something is reduced
有东西被还原
something else is oxidized
就有东西被氧化
So the glucose must be getting oxidized
被氧化的必然是葡萄糖
It becomes this
它变成这个
An oxygen was added here
一个氧被加到这里
Now this process is similar to metabolism in our bodies
这个过程很类似于我们体内的代谢过程
We remove electrons from the sugar we eat
我们也会从吃下的糖中移除一个电子
and transfer them to the oxygen that we breathe
将其转移给我们呼入的氧气
In a reduction reaction like "mirror, mirror"
"魔镜魔镜"这样的还原反应
there might be energy released
会释放出能量
In your body, this energy is harnessed in chemical bonds
人体内,这些能量会用化学键储存起来
stored for later
以便日后使用
The point of Tollens test was not to produce silver mirrors
Tollens测试的本身目的不是为了制造银镜
although a similar reaction is used for that today
虽然现在类似反应确实被用作这个用途
The point was to distinguish between two types of sugars
其本身目的是为了区分两种糖
One is containing aldehydes and one is containing ketones
一种中包含醛,一种中包含酮
Let me draw those
我画一下这些
The difference is that in an aldehyde
差别在于,醛中
the carbon is connected to hydrogen
碳是同氢相连的
and in the ketone, the carbon is connected to another carbon
而酮同,碳是和另一个碳相连的
Aldehydes are more reactive than ketones
醛比酮的反应性更强
so they will react with the silver ions
所以它们能同银离子反应
while the ketones will not
而酮则不能
That's it for me. Hopefully, you enjoyed this video
就到这里吧,但愿大家喜欢这个视频
And I will see you next time
我们下次再见

视频及简介

视频简介:

魔术背后的化学系列视频展示了一些化学实验演示,这些化学实验都非常精彩有趣,创造出各种蒸汽、响声、闪光等引人注目的效果。视频中详细解释了实验背后的科学知识,通俗易懂,寓教于乐。


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