Unit One, Chapter Fourteen - Reaction Feasibility, Standard Enthalpy of Formation, and Entropy Flashcards
What is thermochemistry
The study of changes in energy which occur during chemical reactions
What is the standard enthalpy of formation of a compound
The energy given out or taken in when one mole of a compound is formed from its elements in their standard states
At what pressure is the standard state of a substance most stable
1 atmosphere
At what temperature is the standard state of a substance at its most stable
A specific temperature, usually 298K
What is the entropy of a system
The degree of disorder of the system
Solids have…
Low disorder
Gases have…
High disorder
Entropy increases as…
temperature increases
Changes of state involve…
Changes in entropy
The second law of thermodynamics states…
The total entropy of a reaction system and its surroundings always increases for a spontaneous process
Heat energy released by the reaction system into the surroundings…
Increases the entropy of the surroundings
Heat energy absorbed by the reaction system from the surroundings…
Decreases the entropy of the surroundings
The third law of thermodynamics states…
The entropy of a perfect crystal at 0K is zero
