Talk:Boiling point

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Boiling point elevation in solutions

There should be discussion of the phenomenon of boiling point elevation in solutions, that the boiling point of salt or sugar water is higher than the boiling point of pure water, and why. -- Dominus 05:54 Apr 20, 2003 (UTC)

Mm, colligative properties, you mean (also explains why salt lowers the melting point of ice). I'll see what I can do.DS 14:44, 5 Sep 2004 (UTC)

Could we put the fahrenheit boiling point of water also. My 9 year old daughter attempted to find that value and was frustrated by its absence.Ark30inf 07:19, 20 Aug 2003 (UTC)

It's there now. -- Someone else

Definition

Looking at the definition of boiling and the bit about adding heat not changing the temperature, would a better definition for boiling point be the maximum temperature a a substance can be increased to as a liquid? Martschink 18:04, 24 Jun 2005 (UTC)

You have to talk about the vapor pressure of the liquid and the pressure of the surroundings any time you talk about boiling. If I increase the pressure above a liquid, I will increase the boiling point or if I decrease the pressure, I will decrease the boiling point. Both of these observations result from the changing in the pressure of the surroundings. Boiling occurs when the vapor pressure reaches (incrementally exceeds) the pressure of the surroundings.

I think this article would also be more helpful if it talked about whether or not intermolecular forces or dissolved impurities have anything to do with the boiling point

Dissolved impurities change the boiling point only because they change the vapor pressure of the solution by "diluting" the concentration of the molecules that are producing the vapor pressure. If the dissolved impurity has a higher vapor pressure, it will increase the vapor pressure of the solution and thus lower the boiling point. Dalton's Law of Partial Pressures explains this by saying that the total vapor pressure of a solution is the sum of the partial pressures of each of the components. The partial pressure of a dissolved material (solute if it is a "minority" in the solution) is largely the composite result of the concentration of the solute molecule and the vapor pressure of the solute at the temperature of the solution. If you have something like sugar in water solution (candy making), the sugar has very little vapor pressure. When the temperature of the boiling candy increases, the concentration of water is falling and that of sugar is rising. When you get to the right temperature for the candy, you have really gotten to the desired concentration of water and sugar. The candy thermometer is just a simple way of measuring this concentration. —Preceding unsigned comment added by 70.240.66.35 (talk • contribs) 15 October 2006

Heat and temperature

What is the difference between heat and temperature?

I think that heat (as a noun) is shorthand for thermal energy, and temperature is a ratio between thermal energy and volume. For example, if you were to measure an amount of heat, it could be measured in Joules (or any units for energy), whereas temperature would be measured in J/cm^3 or degrees Centigrade, or whatever. MisterSheik 08:05, 10 Mar 2005 (UTC)

Heat is the average Kinetic energy measured in joules. -Kayla

This comment needs to be deleted, as the answers are flat wrong (and apparently have existed for two years!). For the record, temperature is a measure of the statistical distribution of energy states in a system (which can be measured in units of energy (Joules in SI)) while heat is work done to a system by the exchange of energy states through a reservoir, also measured in Joules. Fundamentally, a change in heat means changes both energy and entropy. SamuelRiv 13:52, 5 November 2007 (UTC)

Facts on Boiling points of various elements

A lot of different sites give different numbers on the boiling points of various elements, particularly Rhenium and Tungsten. This site gives Re's as 5627 and W's as 5660 Kelvin. Wikipedia currently has Re at 5869 and W at 5828 Kelvin. Chemicalelements.com has Re at 5900.15 °K, W at 5933.15 °K. So who do we believe? There's a disagreement that ranges almost three hundred degrees Kelvin here. Mr. Billion 17:49, 24 Jun 2005 (UTC)

First, discount those with the .15 at the end. They are obvious conversions, implying more precision than they actually have, from 5,627 °C and 5,660 °C respectively. Now, surprise, that's what the other site you cited has for the temperature in kelvins. One of them obviously misidentified the units being used. Dig into it with the idea that the actual numbers may be close to those numbers, on some scale.

Of course, the number 5,627 looks pretty suspicious itself, as a likely conversion to degrees Celsius from 5,900 kelvins, without that .15 at the end. Another case where the conversion was probably carried to too many places, but at least they had enough sense to drop those afer the decimal point. I'd suggest 5,900 K with some significant number of kelvins of uncertainty as the likely best value for rhenium.

In general, look first to see if the numbers are more rounded numbers in some other scale. Gene Nygaard 23:55, 24 Jun 2005 (UTC)

At the Help Desk, HappyCamper says he's confirmed that Wikipedia's numbers are correct and that Rhenium has the higher boiling point. But what you're saying seems to cast doubt on what he's saying is correct. Could be his source is wrong, but... I don't know. Mr. Billion 03:23, 25 Jun 2005 (UTC)

I cut "The element with the highest boiling point is Rhenium.". It didn't make sense to say it if the next line discredits it. If you feel strongly for it, put something like 'wikipedia believes', but it cuts down on confusion to just not have it their in the first place. Capi crimm 06:33, 16 July 2005 (UTC)

A number of statements in this article are simply incorrect

The first sentence states:

The boiling point of a substance is the maximum temperature at which a liquid can remain a liquid.

That is incorrect. There is no such thing as "The boiling point". Every liquid has different vapor pressures at different temperatures. Graphs of vapor pressure versus temperature of a liquid are called "vapor pressure curves". Thus, any liquid may have an infinite number of boiling points since such curves have an infinite number of points. The correct definition of a liquid's boiling point is "the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid." Thus, a liquid in a vacuum environment has a lower boiling point than when the liquid is at atmospheric pressure. And a liquid in a high pressure environment has a higher boiling point than when the liquid is at atmospheric pressure. That's how high-pressure steam is made ... by boiling water that is at a high pressure. This is elementary, high school chemistry!

The second paragraph in the article states:

A somewhat clearer (and perhaps more useful) definition of boiling point is "the temperature at which the vapor pressure of the liquid equals the atmospheric pressure."

That is also incorrect. That only defines what is called the "atmospheric boiling point" or the "normal boiling point" ... which is only one of the infinite number of boiling points a liquid may have. The title of this article is "Boiling point" ... it is not "Atmospheric boiling point".

This article was first created in September of 2001, which is over 6 years ago. It is mind-boggling to think that the above definitions were never questioned during all that time. This isn't rocket science or quantum physics, it's simple high school chemistry.

I regret having to be so blunt, but much of this article deserves that bluntness. Wikipedians who don't really understand simple chemistry and physical chemistry should not edit this article. - mbeychok 08:15, 6 October 2007 (UTC)

I think it's best form to introduce the concepts like "boiling point" while relying on as few other complex concepts like "vapor pressure" and "atmospheric pressure" if it is possible. :For instance.. the original, incorrect quote could be appended to read as follows:

"A boiling point for a substance is the maximum temperature the substance can remain before turning into gas."

Then a follow up sentence --like The boiling point for a liquid is dependant upon the pressure of it's environment and the substance's (insert chem word for "inclination to become gassious")-- could be used to refine and expand upon the first sentence's definition; adding a second tier of complexity to that simple matter of chemistry. —Preceding unsigned comment added by 96.18.60.113 (talk) 07:45, 5 December 2008 (UTC)

You're responding to a comment posted over a year ago, and the article has changed since then, and I don't see the troublesome wordings in the current article text. On the other hand, the definitions we have now are multiply cited. I think you have some valid concerns about the style and level of the introduction, but the current statements are verifiably correct. Your statement goes too far, dumbing it down (sorry) until it's not even correct (do solid substances have a boiling point? And liquids can become superheated above their boiling point.) rather than just requiring a less technical background to understand. DMacks (talk) 08:18, 5 December 2008 (UTC)

True about the dates, I posted only for the sake of other readers of the post (I disagreed with his writing philosophy/style as you noted and would promote my own as well), not necisarily in direct discussion with the original poster. When you ask "do solid substances have a boiling point?" I'd say yes because a boiling point is a property of a substance and phase state is another property (substance.phase = gas  ; substance.boiling_point = X if that makes more sense) although maybe the wording could use more thoughtful touch up. You caught me (thx) on the superheated point though, I have to admit, I actually am not too firmilure with that concept at all (beyond "avoid heating things in micros"). There must be a simple clause we could use to create an exception catch for superheated materials, like "A boiling point for a substance is the maximum temperature the substance can reach before it must become gassious *(in a Nucleation-disturbed environment)*." of course Nucleation-disturbed isn't nearly suitible, I just don't know enough about superheated liquids and I should do sleep for a while. You are very true, correctness is more important than understandability, but understandability should be strived for if there are few enough exception clauses required. —Preceding unsigned comment added by 96.18.60.113 (talk) 09:08, 5 December 2008 (UTC)

Difference between boiling point and steam point

Can someone please explain to me the difference between steam point and boiling point?

Or is it the same thing? well what is the boiling point in celsius please —Preceding unsigned comment added by 124.176.44.153 (talk) 05:09, 17 May 2008 (UTC)

I don't know what you mean by "steam point" ... that is some new terminology to me. If you are talking about the boiling point of water, it is 100 °C at sea level atmospheric pressure. But at any other pressure, it would be different. For example, at the top of a high mountain, the boiling point of water is less than 100 °C.

If you will read this article slowly and carefully, you will see that the boiling point of any liquid depends on the pressure surrounding the liquid. You will also see that this article is about any liquid, not just water. - mbeychok (talk) 22:15, 17 May 2008 (UTC)

• • • will you go out with me???? —Preceding unsigned comment added by 76.7.0.108 (talk) 14:19, 15 April 2009 (UTC)

never mind i don't want to anymore

Use understandable language

My kid looked up the defintion of boiling point here on Wikipedia and got a headache. This is overly complicated. Give a basic laymen term definition then go into the doctoral-orgasmic Ph.D. bulls**t. —Preceding unsigned comment added by 71.188.231.28 (talk) 23:32, 17 February 2010 (UTC)

Perhaps the Simple Wikipedia would be a good place to turn when the English one gets too technical? The "Simple English" in the left margin goes to a page that is more in tune with what a lay reader probably wants. It's no excuse for the inaccessible mess here, but it's a good trick in general for readers to know. Feel free to suggest specific improvements...Wikipedia is the encyclopedia anyone, even frustrated readers, can edit. DMacks (talk) 04:07, 18 February 2010 (UTC)

what is principle of boiling point and melting point?