< NEWTON, Ask a Scientist at Argonne National Labs
Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Phase Change: Exothermic or Endothermic
Name: Unknown
Status: student
Grade: 6-8
Location: VA
Country: N/A
Date: 12/29/2004

Is the process of sublimation endothermic?

Sublimation is the transition of a solid [S] to a vapor [V]. Evaporation (boiling) is the transition of a liquid [L] to a vapor [V]. Melting (fusion) is the transition of a solid [S] to a liquid [L]. These are the most common types of changes of the physical state of a substance, but not the only ones. In the direction as written above: [S] ---> [V], [L] ---> [V], and [S] ---> [L] all the transitions require the absorption of heat and so are endothermic. The reverse transitions [V] ---> [S], etc. give off heat and so are exothermic. Some substances have more than one crystal structure, or form glasses instead of crystalline solids, and in the case of hydrogen and helium have weird types of transitions. In these cases it is not always self evident whether a particular transition process is endothermic or exothermic.

Vince Calder

Click here to return to the Chemistry Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory