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Based on this answer: Why add salt to potato water?

I always thought that water boiling was about getting the water to a specific temperature. You can't really get the water to a temperature past that point because as soon as it does it becomes vapor. You can stick it in a pressure cooker (again, the whole point from what I understand) to reach higher temperatures, but you'll never get past boiling. Also, it always takes longer to boil things at higher altitudes because of the reduced pressure and thus reduced vapor temperature of water.

But, I don't know everything (almost, but not quite). Is there something special about water that's vaporizing when it comes to cooking things? Could you really reduce the energy spent cooking something by lowering the vapor temperature of the fluid you're cooking in?

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You're basing this question on an incorrect answer. Like you said, the boiling temperature of water is lower at higher altitudes, which means it takes longer to cook things in boiling water, due to the lower temperature. There's no benefit that I'm aware of in intentionally lowering the boiling point of water (which a pinch of salt does not do, anyway). If you wanted to cook something in water at a lower temperature, you can always just use less heat to keep it below the boiling point.

Put another way, water that is boiling at 190°F does not cook food at the same rate that water boiling at 212°F does, even though they are both boiling.

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  • Yeah, thought so.
    – Edward Strange
    Feb 17, 2011 at 19:46
  • Correction: Adding salt to water does not lower the boiling point at all. It raises the boiling point (albeit by a trivial amount).
    – Aaronut
    Feb 17, 2011 at 19:53
  • @Aaronut Oops, you're right. Salt raises the boiling point, but lowers the freezing point of water. That wrong answer (and first comment) confused me into thinking that it lowered it by a trivial amount instead. Edited my answer.
    – Bob
    Feb 17, 2011 at 20:58
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    The amount of salt you would need to add to make any difference in boiling point would make whatever you cooked in it inedible. For 1 kg (1 l) of water, the boiling point increases by 1.024 degrees Celsius for every 58.43 grams (1 mole). Altitude drops the temp 1 degree C for every 1000 ft.
    – Chris Cudmore
    Feb 18, 2011 at 23:08

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