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Q: How fast does boiling water cool? ( No Answer,   5 Comments )
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 Subject: How fast does boiling water cool? Category: Science Asked by: coos-ga List Price: \$50.00 Posted: 15 Jul 2006 12:56 PDT Expires: 14 Aug 2006 12:56 PDT Question ID: 746621
 ```How long would it take for boiling water to cool to the following temperatures? (all degrees in fahrenheit) 165 170 180 200 All measurements should be done in a 47oz kettle. For example, if I boil water in a tea kettle, how long would it take to reach 180 degrees after I take it off the heat? 1 minute, 2 minutes, 2 minutes and 30 seconds, 10 minutes?``` Request for Question Clarification by answerguru-ga on 15 Jul 2006 13:21 PDT ```Hi coos-ga, In order to answer this question it is also necessary to provide the temparature in the environment around the kettle (ambient temperature). Obviously if you stick your kettle in a sink full of cold water it will cool far quicker than if you just left it in room temperature :) Let me know and I can calculate this for you. Cheers, answerguru-ga``` Clarification of Question by coos-ga on 15 Jul 2006 16:01 PDT `The environment would be room temperature` Request for Question Clarification by welte-ga on 08 Aug 2006 15:28 PDT ```Hi coos-ga, Are you talking about idealized "47 oz. of water" at standard temperature and pressure, without regard to the kettle and such? -welte-ga```
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 Subject: Re: How fast does boiling water cool? From: qed100-ga on 15 Jul 2006 16:19 PDT
 ```*Boiling* water cools at exactly the same rate at which it is being heated. It is at thermal equilibrium, and its temperature remains at the boiling point until the source of heat input is removed. :)```
 Subject: Re: How fast does boiling water cool? From: canadianhelper-ga on 15 Jul 2006 20:59 PDT
 ```Good point! But yes...to answer the question you MUST provide an ambient temperature. Room Temp isn't precise enough ... is the room in Tahiti or the North Pole? Also...where in the water are we measuring the temperature? Is the surface not going to cool faster than the middle of the water? And the dimensions of the jug matter as well. Is it tall and skinny or short and fat. And the composition of the kettle. Is it insulated? Is it Aluminum, Copper, Steel. etc etc. There are alot of variable yet to define. Here are some notes for you to review including a piece on Newton's Model of Cooling. http://www.math.montana.edu/frankw/ccp/modeling/simple/winter/body.htm```
 Subject: Re: How fast does boiling water cool? From: toufaroo-ga on 16 Jul 2006 05:08 PDT
 ```Wowza - \$100 to answer this question? Yikes! To know exact values, one would also need to know the dimensions of the kettle. I know it's 47 oz, but a proverbial "spherical kettle" will behave differently than a "very large but shallow" kettle. Surface area is the important factor here. What's the altitude where you are? Unless you're at sea level, or reasonably close to sea level, your boiling water will not be at 212 degrees. For instance, where I grew up in Colorado, water boiled at just a smidge under 200 degrees! Barometric pressure will also (to a much smaller amount) affect your boiling water temperature. The 212 degree value assumes a standard atmosphere, meaning 1013.2 millibars of pressure and at sea level. Also, what material is the kettle composed of? I'd assume steel, but I've seen kettles in plastic (the electric ones), aluminum, copper, ceramic, etc... Next, where are you placing the kettle? What will the bottom be in direct contact with? If you're hanging the kettle, for instance, then it would be in direct contact with air. If you're placing the kettle on a cold metal table, results will vary. Finally, will the lid be left on the kettle, is it one of the whistle types, etc. All that information will play a vital role in determining the temperature/time information you are looking for if you want to solve analytically to a high degree of accuracy. An easier solution: buy a thermometer and measure the water temperature at 1, 2, 3, or 5 minute intervals. You can then form yourself a plot of water temperature vs time for your specific kettle and your specific conditions. The whole experiment shouldn't take more than an hour and at the end, your data will be much more accurate than any analysis could hope to be.```
 Subject: Re: How fast does boiling water cool? From: toufaroo-ga on 16 Jul 2006 05:13 PDT
 ```I forgot to mention that also, Relative Humidity will also be an important factor, unless your kettle is sealed. The drier it is, the more water will evaporate from the kettle, causing cooling due to evaporation, which means two things...1) your water will cool faster, and 2) since some of the water evaporates, you now have less water in your kettle, so your water will cool faster. Another thing: how much water is in the kettle? It is 47 oz of fluid, or is that just the advertised kettle size?```
 Subject: Re: How fast does boiling water cool? From: thalmaturge-ga on 31 Jul 2006 03:11 PDT
 ```Your question refers to boiling water and temperatures that are below the temperature at which water boils at atmosphetic pressure (1014.25 mbar). If the water is to continue to boil at these lower temperatures then the gas pressure on its surface must have been reduced. The water will boil until it has lost sufficient heat to freeze, after which it will sublime. If it is not to freeze then heat must be added. There is no mention of any added heat, ie take it off the fire then puting it back on again which would change the time taken to reach any given temperature.```