Wierd question

[kewell_]

So when the water on his tongue was boiling it wasnt necessarily that hot? It was just that the water was able to boil at a lower temperature because of the drop in ambient air pressure?

 

[MeteorWayne]

That's correct. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[dragon04]

Exactly. If you wished to hard boil an egg in a hard vacuum, it wouldn't help at all that the water boiled at 0C or whatever.<br /><br />Atmospheric pressure, and atmospheric pressure alone determines the thermal benefits of boiling water.<br /><br />Water is unique because of its properties. CO2 for example simply sublimates at the tiniest fraction of a degree above what keeps it frozen. It goes from a solid to a gas without a liquid phase.<br /><br />Think about a could Alka-Seltzer tablets the next time you use one. Plop plop, fizz fizz. They "boil", but they won't give you nicely cooked foot long hot dogs.<br /><br />Boiling liquid water and the heat it takes to make it boil is directly dependent on the ambient atmospheric pressure. At an altitude of 100,000 feet, you wouldn't even get a decently warm cup of tea. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[kewell_]

If water in the mouth starts to boil, why dont other things in our body start to boil (eg. blood) since we have so much water in our body?

 

[MeteorWayne]

It's not directly exposed to the vaccuum, being in elastic blood vessels, and an elastic skin. Sort of like a pressure suit for the liquid.<br />That's my guess anyway. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[dragon04]

There is a certain amount of resistance to hard vacuum that our cell walls have.<br /><br />The more porous (or less rigid) those structures, the more quickly the walls will fail. A capped PVC pipe full of water for example would allow for the water to not boil.<br /><br />A water balloon might have a problem, though. <img src="/images/icons/wink.gif" /><br /><br />Hard vacuum is trying to "pull" anything it encounters apart from every angle with equal force. <br /><br />If you over inflate a balloon, what happens? It pops. The vacuum of space makes it much easier for that to happen. <br /><br />The same thing applies to a water molecule. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[derekmcd]

Probably because it is protected by the skin. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>It's not directly exposed to the vaccuum, being in elastic blood vessels, and an elastic skin. Sort of like a pressure suit for the liquid. <p><hr /></p></p></blockquote><br /><br />Correct. The pressure will be too low to sustain life, but it will be sufficient to keep the boiling point higher than 97.6 F (average human body temperature). You will experience other difficulties, however, that are related to a sudden drop in pressure -- in particular, some of the nitrogen will come out of solution in your blood, forming painful (and potentially fatal) bubbles.<br /><br />Getting back to boiling, one of the reasons why Earth is special is that the temperature and ambient pressure is generally above water's "triple point". The triple point is a combination of temperature and pressure such that all three phases of a substance (solid, liquid, gas) can coexist in equilibrium. For water this is . . . (looks it up) . . . 273.16 kelvins (0.01 °C) and a pressure of 611.73 pascals (ca. 6.1173 millibars, 0.0060373057 atm). That's from Wikipedia, BTW. Yet we are <i>below</i> carbon dioxide's triple point. This is why dry ice goes straight from a solid to a gas (and probably why it came to be called "dry" ice). To liquify CO2, you have to bump up the pressure considerably. Look closely at the next truck you see carrying CO2; it'll have a pressure gauge on there somewhere. That trailer isn't just a tank -- it's a pressure chamber.<br /><br />This also highlights one of the problems with life on Mars. Although there is air, there isn't enough pressure to liquify water except in very low-lying regions. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>