How do we assess the enthalpy change in phase transitions?

1 Answer
May 25, 2017

Answer:

You must look at the individual phase transitions.......and decide whether bonds are made or bonds are broken.............

Explanation:

When bonds are made energy is released; when bonds are broken energy is absorbed......

#"Ice melting"#: #H_2O(s) + Delta rarr H_2O(l)# #" ; endothermic"#

#"Steam condensing"#: #H_2O(g) rarrH_2O(l)+ Delta# #" ; exothermic"#

#"Water freezing"#: #H_2O(l) rarrH_2O(s)+ Delta# #" ; exothermic"#

#"Water boiling"#: #H_2O(l) +Delta rarrH_2O(g)# #" ; endothermic"#

In each case the making of bonds entails an exothermic reaction.