# Chapter18 - Chapter 18 Entropy Free Energy and Equilibrium...

• Notes
• 8

This preview shows pages 1–3. Sign up to view the full content.

Chapter 18. Entropy, Free Energy, and Equilibrium 18.1 The Three Laws of Thermodynamics Thermodynamics - the scientific discipline that deals with the interconversion of heat and other forms of energy First Law of Thermodynamics - (Chapter 6) energy may be converted from one form to another, but cannot be created or destroyed. (one way to measure: H ) Second Law of Thermodynamics - explains why chemical processes tend to favor one direction Third Law - extension of the second law and only briefly examined in this course 18.2 Spontaneous Processes and Entropy Spontaneous processes water runs downhill salt dissolves in water heat moves to colder object iron rusts methane burns (exothermic, H = -value) acids neutralize bases (exothermic, H = -value) ice melts at room temperature (endothermic, H = +value) ammonium nitrate (NH 4 NO 3 ) dissolves and solution gets cold (endothermic, H = +value) WHY? Two factors effect spontaneity of any change or reaction 1. Enthalpy (H) exothermic processes (negative H) tend to be spontaneous, but not always 2. Entropy (S) - degree of disorder or randomness

This preview has intentionally blurred sections. Sign up to view the full version.

2 18.3 Entropy An ordered state has a low probability of occurring and a small entropy , while a dis ordered state has a high probability of occurring and a high entropy . change in entropy: S = S final - S initial analogies: deck of cards, socks in drawer, molecular motion for a reaction: S = S products - S reactants positive S means: an increase in disorder as reaction proceeds products more disordered (random) than reactants S gas >> S liquid > S solid Figure 18.3, 4 - examples of increasing entropy Soln >> solvent or solute temperature increase – more molecular motion for a reaction, positive S favors spontaneity 18.4 Second Law of Thermodynamics
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern