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A quick Google tells me "Because water boils at a lower temperature at high altitudes". But I am not being able to understand this answer and fill-in the gap. Like, how does an egg cook in the first place? What does it mean when we say that water boils at lower temperature? In fact, I would have thought otherwise that since water is able to boil at low temperature itself (which will be reached sooner), the egg will be able to cook sooner.

What is wrong with this reasoning?

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2 Answers 2

up vote 3 down vote accepted

Since at higher altitudes, the air pressure is lower, the boiling point of water decreases, since it's easier for the energy insde the water to get free.

When A liquid starts to boil, you reach a critical point where the liquid loses a lot of heat, much more than when not boiling, thus requiring much more energy for the same increase in temperature, and lowering the equilibrium point where the flame cannot increase further the temperature of the liquid.

An egg cook because the heat transform the proteins inside, tangling them with each other. But since the boiling water has a lower temperature, this process is slightly slower.

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Found a very good link at: http://www.chemistry.co.nz/cooking_altitudes.htm

Explains things in just the way I wanted them to be explained.

Also the link http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/melting.php section Boiling Point is useful.

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This temperature (in Fahrenheit!) multiplied by time is total nonsense! In general, that stories about long times to hardboil eggs on mountaintop are vastly exaggerated. Doubling up to max tripling reaction time for 10 °C less is realistic. –  Georg Oct 29 '11 at 18:30
    
I don't buy that exact formula of multiplying temperature by time..but it gave me a sense of why it would at least boil slower..-- I am only looking for an inuition.. –  xyz Oct 30 '11 at 7:29

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