The higher the number, the more basic the solution

pH值越高，表示溶液碱性越强

the lower the number, the more acidic

pH值越低，表示酸性越强

So our solution started off basic

我们的溶液最开始是碱性的

It was blue and had sodium hydroxide in it

它是蓝色的，其中有氢氧化钠

And this is what the chemical structure of the molecule looks like when it's blue

这是指示剂分子呈蓝色时的化学结构

The chemical bonds in the molecule are absorbing

分子中的化学键能够吸收

colors of the visible spectrum that are not blue

蓝色以外的可见光谱

so blue is reflected back to our eyes

所以蓝色反射回我们的眼睛

Now if a compound picks up a hydrogen ion

但如果该化合物结合一个氢离子

which it would if you add an acid to it

加入酸时它确实会这样

the molecule changes color

此时分子会变色

Now it absorbs blue and reflects yellow

它开始吸收蓝光，并反射黄光

Since the colors depend on the structure of the molecule

由于颜色依赖于分子结构

a chemist could reprogram the molecule to switch its color at

化学家可以重新构造分子

other pHs, other numbers on this scale

让颜色变化发生在其它pH值上

That's useful depending on the kind of reactions she may want to study

这对于所要研究的化学反应很有用

Now nature experiments with color all the time

自然界也在不断使用着颜色

Animals use color to avoid predators, attracts mates

动物使用颜色来避开捕食者，吸引配偶

scare off enemies, etc

吓退敌人，等等

Alright, so now let's take a look at

好，我们再来看看

what's happening in the second set of cylinders that started off pink

第二组最开始是粉色的柱形容器中发生了什么

The indicator in there is phenolphthalein

这里的指示剂是酚酞