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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。
v. 执行，运转，举行，表演
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- Hi, I'm Jessica
- 嗨，我是Jessica
- and I'm gonna be talking about a chemical demonstration today that
- 今天我要讲的化学演示
- I like to call let it snow
- 叫作"下雪"
- MIT's Dr. John Dolhun
- MIT的John Dolhun博士
- here he is
- 这就是他了
- and his assistant Arielle are going to perform 2 magic tricks
- 他和助手Arielle将演示两个神奇的实验
- involving superabsorbent polymers
- 用到高吸水性聚合物
- Let's watch as they show us the first one at the Cambridge Science Festival
- 首先来看剑桥科学节上他们所演示的第一个实验
- What I'm going to do is I'm going to pour some water
- 我将倒一些水
- into the beaker that she's holding
- 到她所拿的烧杯
- and you keep your eyes on the beaker
- 你们看好烧杯里的情况
- Bring it down just a bit
- 往下拿一点
- Hold it for me
- 拿好了
- Turn it to them
- 拿给观众看
- We are making snow
- 我们在造雪
- We're making snow today, Arielle
- 我们正在造雪 Arielle
- Oh boy
- 乖乖
- It's so cold and wet. It's just like real snow
- 它又冷又湿，就像真雪一样
- Look
- 看
- So what happened?
- 发生了什么呢
- Well, Arielle was holding a beaker containing some sodium polyacrylate
- Arielle所拿的烧杯中装有聚丙烯酸钠
- which is a polymer
- 这是一种聚合物
- Now a polymer is a big molecule that's a chain of repeating units
- 聚合物是一条由重复单元组成的长链分子
- This is the unit
- 这是重复单元
- And this is what it looks like in a chain
- 这是它们组成链的情况
- Now different chains are held together by crosslinks
- 不同的链由交联连在一起
- The etc just means that this could be thousands of carbons long etc
- (等等)表示这里可以有数千个碳那么长
- This is just a small part of the chain in the polymer
- 这只是聚合物链中的很小一部分
- Now when water is added to the polymer
- 当水被加入到聚合物中时
- it wants to rush into the material
- 水会希望涌入到物质中
- because of the presence of so many sodium and carboxylate ions
- 因为这里有很多钠离子和羧酸根离子
- The water displaces the sodium ions
- 水会结合并移走钠离子
- leaving negatively charged carboxylate ions
- 剩下带负电荷的羧酸根离子
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| 重点单词 | 查看全部解释 | |||
| perform | [pə'fɔ:m] | 联想记忆 | ||
| demonstration | [.demən'streiʃən] | |||
| presence | ['prezns] | |||
| molecule | ['mɔlikju:l] |
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