What substance has the highest melting and boiling point?
Posted 12 July 2006 - 06:34 AM
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.
Posted 12 July 2006 - 06:48 AM
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?
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Posted 12 July 2006 - 11:22 AM
Carbon (as Diamond) mp: 3823 bp: 5100
Tungsten: mp: 3650 bp: 5800
Rhenium: mp 3453 bp: 5900
all temps in Kelvin.
Posted 12 July 2006 - 09:14 PM
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.
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