Is condensing water vapor an exothermic process or an endo process?

1 Answer
Nov 21, 2016

Well condensation is the reverse of vaporization, so it is clearly exothermic.


When we boil water, we put heat into the system:

#H_2O(l) + Delta rarr H_2O(g)#

Now this physical process as written is clearly ENDOTHERMIC. And it makes sense intuitively.

Given this, the reverse process must clearly be EXOTHERMIC:

#H_2O(g) rarr H_2O(l) + Delta#

When you include the #Delta# symbol in your reactions, this can help to rationalize the direction of energy transfer, and whether a process is exothermic etc.