時(shí)差N小時(shí):食鹽大戰(zhàn)冰塊
為什么食鹽能讓冰塊融化?
It lowers the melting and freezing point of water.
是因?yàn)槭雏}將水的熔點(diǎn)和冰點(diǎn)降低了。
Oh,OK.Wait,I don't get it. Doesn't that mean the saltmake ice colder?
等一下，我不明白。這就意味著食鹽讓冰的溫度變得更低嗎?
Let me explain.Pure water freezes at thirty-twodegrees Fahrenheit,right?
我解釋一下。純凈水的冰點(diǎn)是32華氏度，對(duì)吧?
At that temperature we can say that the rate offreezing is the same as the rate of melting.
這個(gè)溫度既是冰點(diǎn)也是熔點(diǎn)。
So in other words, at water's freezing point there's a sort of equilibrium between freezing andmelting.
也就是說(shuō)，水的冰點(diǎn)就是結(jié)冰和融化的平衡。
Right.Throwing salt on ice upsets the balance.
是的。在冰上灑鹽擾亂了這種平衡。
Upsets it how?
怎么打亂的呢?
The salt dissolves into the liquid water, which means that some of the water molecules arereplaced by salt.
鹽溶解在水中，就是說(shuō)一部分水分子被鹽取代了。
Since there are now fewer liquid water molecules to be captured and frozen by the ice, therate of freezing drops.
既然結(jié)冰的液態(tài)水分子減少了，冰點(diǎn)自然降低了。
I think I get it.And Since the rate of melting stays the same, there's more melting going onthan freezing.
我明白了。水的熔點(diǎn)不變，融化的水分子比結(jié)冰的多，
And so the ice melts.
所以冰塊就融化了。
Right.Interesting.
對(duì)。很有趣。
In fact, anything that dissolves in water will do the trick.
其實(shí)，任何溶于水的物質(zhì)都可以使冰融化。
You could pour sugar on ice and it will melt.
把糖灑在冰上，冰也會(huì)融化。
But I guess since salt is cheaper it's used more often.
但是我想也許由于鹽比較便宜，所以經(jīng)常被使用。
