Understanding how the equilibrium constant (Keq) relates to enthalpy change. Introductory thermodynamics. Attachment in Word.

In addition to a full answer, this problem solution provides an explanation of how to approach deciding which reaction is more exothermic, when you have a limited amount of information.  The problem only provided the Keq values, without stating other experimental conditions (such as temperature or reaction components).  This creates a challenging and tricky situation for the student -- you will need to understand thermodynamic equations and relationships, and use that understanding to reason (rather than calculate) which of the two reactions is more exothermic.  Exam tips for this type of problem are also shown in the html version of the solution (but not in the attachment).