The truth about water and its boiling point

I was trying to think of something to write today and it came to me at breakfast with a little extra thought. I was making my morning Double Americano with Fresh Ground Kona Coffee Beans (yes I love Hawaii, but that’s for another post), when it came to me. Why does boiled water seem to re-boil faster? I pondered the thought for a while and even thought about punching in a query into Google, but I thought of a better way.

It seems as though mother’s have been making it into blog posts. BTW, if you haven’t checked out Lyndon Reid‘s mom shotgunning a beer…you need to. My mom would never do something like that, but she is a science geek. In fact she’s got her Ph. D and is a serial cereal chemist for the government. So I decided to email her for some insight (thanks Lyndon for the inspired thought).

Hey mom

I figured I’d ask my favorite Ph D person this question since I figure it’s somewhat science related:

Q: Why does previously boiled water, boil faster the second time around…even the next day?

I was making coffee this morning/afternoon an this definitely happened. I figure since you’re a cereal chemist that typically eats oatmeal (a cereal grain) for breakfast and it requires boiled water you would be able to answer it quickly.

In non-typical government fashion, it didn’t take long for my mother to reply. I had a reply in under 15 minutes (it was actually 12).

As far as I know it’s because you’ve driven most of the air out of it the first time you heated it so when you ‘re-boil’ it the heat transfer is faster – but don’t quote me on it (in your case it could have been that the water you boiled the first time was cooler than when you re-boiled it therefore you wouldn’t have to heat it so long to get it to the boiling point). Where you live there could even be some effects of atmospheric pressure (thought I doubt this).


I always love the TTFN she signs off with in reference to Winnie the Pooh stories. Anyways, back to the thought. It didn’t seem as though her answer was really to concrete on the thoughts. In fact she even says “don’t quote me on it”. So with that I had to hit Google. Low and behold the first result about Water Freezing and Boiling Myths has an answer:

Previously boiled water boils faster than regular water. Likewise, previously boiled water at room temperature should boil faster than water that has never been boiled, for the same reason it freezes faster (less dissolved oxygen).

So mom, it looks like you were right. I guess it’s just further proof that our mothers really are a source of information, knowledge and love. So if you’ve got a beer or glass of wine, raise it in a toast to your mom—or in the case of Lyndon, shotgun it with her!

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