Jump to content


Photo
- - - - -

What substance has the highest melting and boiling point?


  • Please log in to reply
4 replies to this topic

#1 GrandMasterK

GrandMasterK

    Baryon

  • Senior Members
  • 129 posts

Posted 12 July 2006 - 06:09 AM

man made included.
  • 0

#2 woelen

woelen

    Primate

  • Senior Members
  • 1,864 posts

Posted 12 July 2006 - 06:34 AM

I think that carbon (graphite, and diamond) has the highest boiling point. In fact, it sublimes. IIRC, this happens at temperatures between 5000 and 6000 C.

Maybe it is not the compound with the highest boiling point, but it certainly is among the compounds with the highest boiling point.

Of course, all this must be specified at atmospheric pressure. At much higher pressure, such as in the core of the planet Jupiter, even hydrogen can exist in solid or liquid state, while white-hot, with metal-like properties. But that is at a pressure of millions of earth's atmospheres.
  • 0

#3 Rocket Man

Rocket Man

    Molecule

  • Senior Members
  • 576 posts
  • LocationAustralia

Posted 12 July 2006 - 06:48 AM

i think covalent networks will have the higher melting points, but when the bonds break to become fluid, it will have different properties and boil instantly.

perhaps ionic compounds will have the higher boiling points.

the element with the highest melting/boiling point, i think, is tungsten.

slightly off topic, but are there conditions where helium is soild?
  • 0
There's a fine line between genius and insanity, I have erased this line. Oscar Levant

No trees were killed in the sending of this message. however, several million electrons were greatly inconvenienced.

#4 YT2095

YT2095

    Chemistry Expert

  • Resident Experts
  • 16,959 posts

Posted 12 July 2006 - 11:22 AM

according to my data book, the real candidates of the elements would be:

Carbon (as Diamond) mp: 3823 bp: 5100
Tungsten: mp: 3650 bp: 5800
Rhenium: mp 3453 bp: 5900

all temps in Kelvin.
  • 0

#5 raivo

raivo

    Atom

  • Senior Members
  • 215 posts

Posted 12 July 2006 - 09:14 PM

Some carbides have very high melting and boiling points:

ZrC mp 3500C, bp 5100C.
TaC mp 3800C, bp 5500C

Some substances with high melting point become soft like lead much before melting and others may start to react with oxygen and other gases even below 1000C. In practice graphite, carborundum (mp 2800C) and platinum (mp 1770C, bp 3800C) are often used where high heat occurs. Certain carbides and some oxides like Al2O3 (mp 2050C) and MgO (mp 2825C, bp 3600C) are also very common. Tungsten (mp 3420C, bp 5680C) and molybdenum (mp 2620C, bp 4630C) bear high heat very well but only in oxygen-free environment. There are also lot of special alloys that are incredibly strong at 1000C or 1500C but have lower melting points than their constituents.
  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users