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Author Topic: Can water be boiled in a paper cup?  (Read 8038 times)

Anup

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Can water be boiled in a paper cup?
« on: 06/06/2011 05:01:02 »
Anup asked the Naked Scientists:
   
Can water be boiled in a paper cup?

What do you think?
« Last Edit: 06/06/2011 05:01:02 by _system »


 

Offline JP

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Can water be boiled in a paper cup?
« Reply #1 on: 06/06/2011 05:13:26 »
Yes.  Water boils at 100 C and paper burns somewhere in the ballpark of 200 C.  You could certainly heat the paper to 100 C and the water would boil without burning the paper. 

If you put a direct flame to the cup, you should also be ok, so long as the paper is thin and the part of the paper cup touching flame is also touching water.  This is because objects in contact tend to equalize their temperature.  Water boils at 100 C, and it stays at 100 C as you add extra heat to it--you only change the rate at which is boils.  This means the paper touching it wants to stay at 100 C as well and it transfers any extra heat to the boiling water in order to do so.  So if you apply a direct flame to the bottom of a paper cup filled with water, the paper shouldn't burn.  Of course if the paper is thick so that it can't transfer the heat from the outside to the water quickly enough or if the water boils off, then the paper can burn. 
 

Offline Geezer

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Can water be boiled in a paper cup?
« Reply #2 on: 06/06/2011 06:22:37 »
Of course, you could always heat up a rock (quartz is quite good) in a fire, then drop it into the paper cup containing the water. But stand well back, and wear safety glasses.
 

Offline techmind

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Can water be boiled in a paper cup?
« Reply #3 on: 12/06/2011 16:14:08 »
You could also try just microwaving the paper cup of water - but I'd put it in a Pyrex/microwave-safe bowl as well just in case the paper went soggy or the glue came unstuck...

What possible problem did the original poster envisage? Why did they ask? What method of heating were they thinking of?
 

Offline Don_1

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Can water be boiled in a paper cup?
« Reply #4 on: 14/06/2011 09:36:05 »
Paper cups are often used in microwave ovens to cook a whole lot of things. Usually the paper is waxed to prevent the problems techmind mentioned.
 

Offline JP

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Can water be boiled in a paper cup?
« Reply #5 on: 14/06/2011 14:19:00 »
What possible problem did the original poster envisage? Why did they ask? What method of heating were they thinking of?

This is a common experiment to show that water boils at 100 C.  You apply a flame to a paper cup filled with water and show that it doesn't burn when the water boils.  I'm guessing that's what the poster was thinking of, but you could always use a microwave.  :)
 

Offline !mater

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Can water be boiled in a paper cup?
« Reply #6 on: 22/06/2011 16:18:46 »
Couldnt you put water just into vacuum and watch it boil at ten degrees? Its pressure dependent, i heard that on mount everrest water already boils at around 80° degrees. Then again, i got no idea of physics, i might be wrong, and my answere a cheat around the question.
 

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Can water be boiled in a paper cup?
« Reply #6 on: 22/06/2011 16:18:46 »

 

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