<p>Just a quick quesiton. My book says condensation and freezing are exothermic. BUt condensation goes from gas (high enthropy) to liquid (low enthropy) and freezing is liquid (high enthropy) to solid (low enthropy)...so that means it's a negative delta s which means it MUST be a positive delta h. But that can't be since a pos. delta h is endothermic...</p>
<p>This would be better suited for the SAT Subject Test forum.</p>
<p>∆H doesn't need to be negative if ∆S is as well. Gibbs free energy can make a big difference here. The equation relating them is:</p>
<p>∆G = ∆H - T∆S , so you can algebraically derive how ∆H relates as well. Hope that helps :)</p>