Chemistry / Unit 11 Chem 2109 short lesson, about 20 seconds
The Four ΔH/ΔS Sign Combinations
Captions available
The idea
A reaction with ΔH negative and ΔS positive is spontaneous at every temperature; positive ΔH and negative ΔS is nonspontaneous at every temperature; the other two combinations flip.
In practice
Hydrogen peroxide's decomposition to water and oxygen is exothermic and increases gas moles, so it is spontaneous at every temperature.
Where people slip
A negative ΔH alone does not guarantee spontaneity; unfavorable ΔS can push ΔG positive.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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