The same thing is happening as with our bromothymol blue
情况和溴百里酚蓝很类似
but this time when the solution is basic, it's pink
但这次，溶液呈碱性时，它是粉色
and when it's acidic, it's colorless
呈酸性时，则是无色
But why does adding dry ice
那么为什么加入干冰
change the solution from basic to acidic?
会让溶液从碱性变为酸性呢
Well, dry ice is solid carbon dioxide
因为干冰是固态二氧化碳
When you add it to water, it bubbles
加到水中时，它会冒泡
and part of every bubble of carbon dioxide dissolves
每个泡泡中都会有二氧化碳溶解
when it does, it forms carbonic acid. Let's look at that equation
这时就会生成碳酸，我们来看看方程式
So there's more and more carbonic acid in the water
水中的碳酸越来越多
and this acid reacts with the sodium hydroxide until there's none left
这种酸会同氢氧化钠反应，一直将其耗尽为止
So the solution becomes acidic
于是溶液变成酸性
So we saw our bromothymol blue
所以我们看到溴百里酚蓝
turning from blue to yellow as a solution became more acidic
随着溶液酸性越来越强，从蓝变黄
And we saw our phenolphthalein
而酚酞
turn from pink to colorless as it became more acidic
随着溶液酸性越来越强，从粉色变为无色
Now let's watch again what happens in the final set of cylinders
下面再来看看最后一组柱形容器中的实验
Alright, so now, I ask you to focus your attention on this cylinder
好，现在我要求你们注意这个柱形容器
Actually, you can focus your attention on anything you want to
实际上，你们也可以关注别的
You can even not pay attention if you want to
甚至不关注任何东西都行
We live in a free country
我们生活在一个自由的国度
But if you want to follow the experiment with me
但如果你想跟随我的实验步伐
I want you to focus your attention on this one
我希望你能关注这个
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