# The Naked Scientists Forum

### Author Topic: Why is Cooled Boiled Water Good For Baby ?  (Read 11580 times)

#### biomed0101

• Jr. Member
• Posts: 18
##### Re: Why is Cooled Boiled Water Good For Baby ?
« Reply #25 on: 26/08/2005 02:15:29 »
Thank you finchbeak, and thank you on the comment describing the equation of state. Youīre absolutely right pointing our attention on the relationship of P and T not being intricately depending on one another. Boy, the things that a layman forgets.
In the boiling water example, letīs follow what happens. First, the heat energy from the stove is conducted through the bottom of the pan, making the water molecules move around faster (as finchbeak explained, the water temperature rises), we can name this higher kinetic energy. Because of this higher kinetic energy, water can escape the pan in both gaseous and liquid form. This means that the amount of substance (in chemistry denoted as n) decreases. So, if we look at finchbeaks example above, n*R*T isnīt constant, in fact it decreases because of the variable n. Most pure substances, such as water tend to change from liquid into gaseous form at a constant temperature. for water, this is at T=373.2K(100 degrees centigrade). Now, look closely at the pan, itīs fully open to itīs surroundings, here you can conclude that the pressure must be equal to the atmosphere. There, P and T arent intricately related.
Now, if you put a lid on the pan, that doesnīt let out any gas, the kinetic energy of the water molecules bounce off at the walls with higher speeds. (correct me if Iīm wrong) This means that in a given time interval of letīs say one second, more mass units bounce off at the same area than when at lower temperature, thus when we look at the mathematical definition of pressure, p=F/A, we might conclude that p has increased when heated. n didnīt change, because of the lid.

Now, Iīm not really sure if this is correct, but I imagined it this way, with help of my textbooks.

#### gsmollin

• Hero Member
• Posts: 749
##### Re: Why is Cooled Boiled Water Good For Baby ?
« Reply #26 on: 26/08/2005 04:19:16 »
quote:

I give all my jihad children heavy water.

catch me if you can!

"F = ma, E = mc^2, and you can't push a string."

#### gsmollin

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• Posts: 749
##### Re: Why is Cooled Boiled Water Good For Baby ?
« Reply #27 on: 26/08/2005 04:28:36 »
Back on topic, I'm pretty sure it all comes down to pathogens in the water supply, and boiling used to be good advice, since it will kill most bacteria. However, it does not kill all protozoans, especially cryptosporidian oocysyts and sporozoites. These tough organisms are the ones most likely to escape a public super-chlorination system. To kill crypto, you should be using a special water filter. Here's a page about water filtration, and it has a link to the UK water inspectorate. Of course, they are selling, but crypto is the most serious water borne threat to the newborn.

http://www.1x1x1.co.uk/water/filtration/water_biology.htm

"F = ma, E = mc^2, and you can't push a string."

#### neilep

• Withdrawnmist
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##### Re: Why is Cooled Boiled Water Good For Baby ?
« Reply #28 on: 26/08/2005 14:22:49 »
quote:
Originally posted by gsmollin

However, it does not kill all protozoans, especially cryptosporidian oocysyts and sporozoites. These tough organisms are the ones most likely to escape a public super-chlorination system. To kill crypto, you should be using a special water filter. Here's a page about water filtration, and it has a link to the UK water inspectorate. Of course, they are selling, but crypto is the most serious water borne threat to the newborn.

http://www.1x1x1.co.uk/water/filtration/water_biology.htm

"F = ma, E = mc^2, and you can't push a string."

Thank you gsmollin, and the link is appreciated...however, I'm a dab hand with a pair of tweezers and a magnifying glass and I reckon I've got the cryptosporidian oocysyts and sporozoites under control !!

Men are the same as women.... just inside out !!

#### The Naked Scientists Forum

##### Re: Why is Cooled Boiled Water Good For Baby ?
« Reply #28 on: 26/08/2005 14:22:49 »