What is the standard enthalpy of atomization?

1 Answer
Truong-Son N.
Jan 10, 2017

The standard enthalpy of atomization, #DeltaH_"atom"^@#, for atoms is just for the process of converting however many #"mol"#s of the standard state (i.e. at #25^@ "C"# and #"1 atm"#) of the element needed to make #"1 mol"# of its gaseous form.

Thus the #DeltaH_"atom"^@# of #"Cl"_2(g)# to #"Cl"(g)# is for this reaction, for instance:

#1/2"Cl"_2(g) -> "Cl"(g)#

which is really half the enthalpy of breaking the #"Cl"-"Cl"# bond of #"1 mol"# of #"Cl"_2(g)# molecules, at #25^@ "C"# and #"1 atm"#.

For #"Cu"(s)#, which is a transition metal, its #DeltaH_"atom"^@# is based on the reaction:

#"Cu"(s) stackrel(Delta" ")(->) "Cu"(g)#

which in this case is really the enthalpy of sublimation for copper solid, at #25^@ "C"# and #"1 atm"#.

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