Brain Teasers
Hot Steam
Which is more dangerous, steam at 100 degrees C, or steam at 150 degrees C?
Hint
What is the most dangerous aspect of steam?Answer
The 100 degree C steam. The most dangerous aspect of steam is the latent heat released when it condenses. This is much greater than the heat capacity of steam or liquid water. The 100 degree C steam can condense as soon as it contacts your skin. The 150 degree C steam is further from the boiling point and most likely will not condense once it touches your skin.Hide Hint Show Hint Hide Answer Show Answer
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This is one of those teasers that is counter-intuitive, and that makes it all the more enjoyable.
You're ignoring the fact that if you have 150 degree steam, then the pressure is around 67 psi, which is dangerous in itself. Also, this is time-dependent. Give it enough time and the 150 degree steam will condense, burning you worse because of the higher temperature. This is a good idea, but the teaser really needed more details.
Actually, on second thought, I'll take back the first sentence above, but repeat that there isn't enough detail here. What is the pressure in each case? Time of contact? What do you mean by "more dangerous"? I don't mean to sound too picky, but you need to cover all of your bases with science teasers. I could come up with several situations in which the 150 degree steam is "more dangerous". This includes the hint, too. In certain situations, the "most dangerous aspect of steam" is its pressure. Details, my man, details!
When comparing the two steams, it is obvious that they have to be at the same pressure. Since I said one the steams was at 101 degrees C, then the pressure is near 1 atm or 14.7 psi. The 150 degree steam is superheated and is less likely to condensate immediately on your skin. I could have given the pressure in the question, but I really doubt people have access to thermodynamic steam table charts that tell them the boiling point of water at different pressures. So I just made it obvious that the pressure is 1 atm. Ideally, the situation would be that the pressure would be greater than 1 atm and this is a question of what would happen if there were a leak in a pipe line caring steam. Yes, given enough time it will condensate on your hand, but since is this a COMPARISON you don't need to know the time, you just need to know that the 101 degree C steam will condensate quicker and it will burn you quicker. That is one of the reasons why pipes caring steam are usually superheated. If you were next to a break in a pipe line and the steam was near saturated, you would walk away scolded. But if the steam was superheated, you could get out of the way before you got burned. So my point is that the time is irrelevant, the pressure is irrelevant, and the problem was designed to inform people of the relative danger of steam and the teaser is stated just fine. If I gave too much detail, it would require people to find a thermodynamic book to solve the problem, which would make it too hard. And probably the only person with that kind of access would be me. I was just trying to get the point accross that in an industrial setting, low temperature steam is more dangerous to people than high temperature steam at the same pressure. Get it now?
On second thought, maybe I could have added to the teaser that the steam was at the same pressure to make it less confusing to people.
1. The pressure is NOT obvious. It must be assumed becasue you didn't say what it was. Steam table or no steam table, the pressure has to be known to answer the question. For all I know, the 100 degree steam is supersaturated steam at 0.5 atm. 2. The COMPARISON is definitely time-dependent, becasue your answer is generally correct for short times but incorrect for long times. If I had to be exposed to steam for 10 minutes I would rather be exposed to the 100 degree steam because it possesses less total energy. 3. "More dangerous" is not specific enough. If the steam is flowing through an uninsulated pipe, then the 150 degree pipe will burn you more than the 100 degree pipe will because the temperature is the deciding factor. I get the point that you're trying to illustrate with this teaser, but I still think that more details are needed. You have to be careful with science teasers and cover all bases, or some yahoo like me with too much time on his hands will tear them apart. ...and I speak from experience because I've been on the receiving end.
I'll keep in mind that most people, even 3 level editors of this website, don't have enough intuition to figure out the obvious. From my engineering background, when comparisons are made, assumptions are not stated, they are figured out. I rarely got a problem that stated assumptions. Almost every problem I have ever had to solve, I had to figure out the assumptions on my own. This is because when comparisons are made, EVERYTHING else is held constant. I should have realized that people will put there own twist on a teaser and come up with wild ideas. Of course if you were tortured, it wouldn't make much difference which steam your were exposed to, you'll get burned badly either way. But since most people are not held down most of the day I thought it would be obvious that a person could get out of the way quickly after being exposed. The dangerous part is specific enough because danger indicates an immediate threat to you well being. Remember, it is the steam that will be exposed to a person in this problem, not the pipe that is carrying it, so the pipe comment is irrelevent. The problem simply asks which is a more immanent threat to your well being (danger), saturated steam or superheated steam, just the steam and nothing else. Do you get why there isn't any other detail. Nobody can cover every little detail that a reader might think of when writing a teaser. The lack of detail kind of implies that the problem is intended to be straight forward. Let me reiterate: 1) It is a comparison, everything is held constant. Same time exposure, same pressure, etc. 2) Danger is specific enough, it is an immanent and immediate threat to your well being. So the more dangerous part implies which one will hurt you the quickest. I didn't ask which one will hurt you the most in the long run. 3) The lack of detail kind of implies that it was intended to be straight forward. Just comparing exposure to steam at different temperatures. Not the pipe they are in or the idea that you could be in a torture chair and being exposed to steam for long periods of time to make you talk.
Ok. Instead of picking apart everything you just said, I'll do this: Explain to me, please, why the following is not a perfectly valid (and arguably better) answer to your question AS IT IS WORDED: The 150 degree steam is more dangerous because it possesses more latent heat. It has the capacity to transmit a greater amount of energy to whatever it comes in contact with and can therefore cause more damage than the 100 degree steam.
The 150 degree steam at the same pressure doesn't contain any more latent heat than the 101 degree steam. Latent heat is the energy change from a phase change. The 150 degree steam does contain more energy in the form of heat capacity. Like I tried to explain in my previous comment, danger refers to an immediate and immanent threat. The 101 degree steam will condensate immediately and the 150 degree steam will take a while. Most likely, if a break in a steam line occurs, the 150 degree steam could just brush past your skin. I should inform you that this teaser is just a question that was asked in one of my thermodynamic classes (I have taken several.) The person who asked it was a Ph.D, with years of teaching experience and was an expert in thermodynamics. Have you ever wonder why hot water stays hot for so long. It is because it has a high heat capacity. It takes a lot of energy removal to decrease the temperature of water by one degree. Steam has almost as high of a heat capacity as liquid water. The 150 degree steam will take a while to drop down to 100 degrees when it then can condense. During a break in a pipe, the steam would be nowhere near your skin when it reaches 100 degrees if you were standing next to the pipe. Lets compare again. 101 degree steam, condensates almost immediately and burns you; 150 degree steam has to cool a significant amount first and condensates after it has brushed past your skin or after you have left the area.
First off, in my last post, the word "latent" shouldn't be there. I meant that the 150 degree steam has more TOTAL heat, and can therefore be considered more dangerous. Again, I'm not arguing that the scientific fact in this teaser is incorrect. The question is just too vague. The word "Dangerous" has no time dependency in it. Look up "danger" on Dictionary.com. There is nothing about the threat being "immediate". 150 degree steam can be considered more dangerous because it possesses more heat. If you want to rule out this answer you have to clearly state that short times are involved in the question, or possibly describe a situation where a person is surprised by a burst in a steam pipe.
Oh, by the way, it's been a long time since I've had a good back-and-forth like this (see the teaser "Crazy Math" for my last good one - you can feel my frustration oozing out of the monitor). Anyway, I hope you don't feel that I'm coming on too strong or mercilessly bashing your teaser. That's not my intent. Science teasers are among my favorites so I put more thought into them than other teasers, and I always like a good logic/science discussion. And to show my sincerity, here's a few smileys for you:
Don't worry about insulting me. I have fun debating people. You tend to learn more because you are exposed to the opposite side of your view and you have to think a lot to make your point of view stronger. You and I have a lot in common, neither of us are willing to back down. So with that in mind you know that I can't let this rest. I've got my dictionary right here in front of me. (Webster New World College Dictionary)
Dangerous: full of danger; likely to cause injury, pain, etc.; unsafe; perilous.
Peril (as a synonym of danger): suggests great and imminent danger.
Imminent: Likely to happen without delay; impending; threatening: said of danger, evil, misfortune.
From these definitions, it seems that dangerous has a factor of time involved with it. So I still stand behind my words; the first to hurt you is the most dangerous. The idea behind my debate is that you will not walk away unscathed from being exposed to steam that is saturated but you will most likely escaped unharmed from being exposed to superheated steam.
Dangerous: full of danger; likely to cause injury, pain, etc.; unsafe; perilous.
Peril (as a synonym of danger): suggests great and imminent danger.
Imminent: Likely to happen without delay; impending; threatening: said of danger, evil, misfortune.
From these definitions, it seems that dangerous has a factor of time involved with it. So I still stand behind my words; the first to hurt you is the most dangerous. The idea behind my debate is that you will not walk away unscathed from being exposed to steam that is saturated but you will most likely escaped unharmed from being exposed to superheated steam.
Hey Bobbrt, do you have to accumulate a certain number of points before being allowed to send a private message to a person on a buddy list? I tried to send you a private message because it didn't relate to this topic but all I got was a page that said that I needed to login first, but I was already logged in.
Those that live by the sword Curtis..... . Anyway, good teaser; I learned something.
All right - answer me this: Which is more dangerous - getting pricked with a needle RIGHT NOW or catching AIDS? And to help you, I'll repeat your words: "The first to hurt you is more dangerous". CHEW ON THAT ONE, SCIENCE BOY!!! MUAHAHAHAAAA!!!!
Oh, and to illustrate the danger of using synonyms (as you did with "peril"): Risk is a synonym of Danger. Exposure is a synonym of Risk. Acknowledgment is a synonym of Exposure. Recognition is a synonym of Acknowledgment. Respect is a synonym of Recognition. Adoration is a synonym of Respect. (Source: Dictionary.com). So using the commutative property, Danger is synonymous with Adoration. And I must say that I truly ADORE 150 degree steam.
Oh, and I'm not sure what's wrong with your Private Messaging. I'll send you a PM, and you can see if you can at least respond to it.
Hey, I think this is going a little too far. Comparing getting pricked by a needle is not even in the same ball park as getting AIDS. But if the needle causes an infection and you die or have an arm amputated, then yes getting pricked by a needle is more dangerous than getting AIDS. This kind of explains why they swab a prisoner's arm with alcohol before they give them the lethal injection. The way that you went from one word to another by using synonyms makes it seem that if you go through enough word you can make any two words synonyms. I used peril because perilous was a definition of dangerous.
Bobbrt, I think there is something wrong with my ability to send or receive private messages. I never got you message. Maybe I am looking in the wrong spot. But I have clicked on every link on this website. I can't send private messages and I can't post replies to topics on the message board. I clicked on the contact link at the bottom of the page and sent a message telling who ever reads them about my problem.
Well, normally if you click on "Message Board" on the right and then "Private Messages" in small print at the top of the Message Board page, you will be able to see your messages. If this isn't workin for you, you'll have to check with Jake. Unfortunately, I can't help you.
WOW! Some people have WAY too much time on their hands!
I dont reallyunderstand all this scientific stuff your saying but I do think it was fairly obvious that the pressure of the steam is the same unless stated? :S
And you cant get 150 degree steam because water boils at 100 Degrees
There is no upper limit on the temperature of steam because it is in the gas state. Liquid water on the other hand has a limit and it is 100 degrees C at 1 atm.
Jan 21, 2004
Um, that whole debate thing was kind of over the top. I'll say two things: First, I agree with Curtis. Second, it was dang fun that bobbrt typed "bwahahahahahah!" Anyway, isn't this more of a science QUESTION rather than a teaser?
Not bad, I liked this one!
I think this teaser is A) missing a question mark and B) too simply stated. To be a really good teaser you should set up an interesting situation that involves the science concepts as part of the story. Not just copy a question from a science test.
I do have to agree with the answer to this one though.
I do have to agree with the answer to this one though.
i think curtiss should have his teaser submission priviledge halted, immediately. buddy, all you do is look up the most vague facts about the most pointless concepts, and copy questions that you can't even answer, nor defend. this whole debate takes away the fun of a TEASER. this is not called 'stump everyone to make myself appear smart' but that seems to be what you want to play, and you can't even figure out how to send a message? and you go to MIT? i don't live in the US, thankfully. anyways, try submitting a teaser, something fun that has an answer that people can figure out, and not have to look up thousands of years of reasearch (BTW-copying your professors work and passing it off as your own....don't people get kicked out of prestigious schools for that?)
Hmmm...wouldn't both samples at the same volume and pressure contain the same amount of energy? As long as theyre in the same phase?
The problem didn't state anything about the volume. If it did, having both at the same volume and pressure doesn't mean that they both have the same energy. And it's not about the energy content (which is obvious because they have different temperatures while everything else is held constant and therefore they have different energy content.) It's about which one is on the verge of condensing and thus unleashing a very large amount of latent heat. The latent heat released by steam is the main culprit in causing burns.
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