The higher the number, the more basic the solution

pH值越高，表示溶液堿性越強(qiáng)

the lower the number, the more acidic

pH值越低，表示酸性越強(qiáng)

So our solution started off basic

我們的溶液最開(kāi)始是堿性的

It was blue and had sodium hydroxide in it

它是藍(lán)色的，其中有氫氧化鈉

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

這是指示劑分子呈藍(lán)色時(shí)的化學(xué)結(jié)構(gòu)

The chemical bonds in the molecule are absorbing

分子中的化學(xué)鍵能夠吸收

colors of the visible spectrum that are not blue

藍(lán)色以外的可見(jiàn)光譜

so blue is reflected back to our eyes

所以藍(lán)色反射回我們的眼睛

Now if a compound picks up a hydrogen ion

但如果該化合物結(jié)合一個(gè)氫離子

which it would if you add an acid to it

加入酸時(shí)它確實(shí)會(huì)這樣

the molecule changes color

此時(shí)分子會(huì)變色

Now it absorbs blue and reflects yellow

它開(kāi)始吸收藍(lán)光，并反射黃光

Since the colors depend on the structure of the molecule

由于顏色依賴于分子結(jié)構(gòu)

a chemist could reprogram the molecule to switch its color at

化學(xué)家可以重新構(gòu)造分子

other pHs, other numbers on this scale

讓顏色變化發(fā)生在其它pH值上

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

這對(duì)于所要研究的化學(xué)反應(yīng)很有用

Now nature experiments with color all the time

自然界也在不斷使用著顏色

Animals use color to avoid predators, attracts mates

動(dòng)物使用顏色來(lái)避開(kāi)捕食者，吸引配偶

scare off enemies, etc

嚇退敵人，等等

Alright, so now let's take a look at

好，我們?cè)賮?lái)看看

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

第二組最開(kāi)始是粉色的柱形容器中發(fā)生了什么

The indicator in there is phenolphthalein

這里的指示劑是酚酞