Chapter03

Chapter03 - BCH 4053Spring 2003Chapter 3 Lecture Notes...

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Chapter 3, page 1 BCH 4053—Spring 2003—Chapter 3 Lecture Notes Slide 1 Chapter 3: Thermodynamics of Biological Systems Slide 2 Energy and Work • Work = force x distance • Energy = ability to do work • Mechanical Energy • Kinetic Energy = mv 2 /2 • (Energy from motion) • Potential Energy • (Energy from attraction or repulsion) Both Work and Energy are products of intensive and extensive factors: force x distance (mechanical work) pressure x volume change (work of expansion) voltage x current (electrical work) etc. One of the triumphs of the energy concept was the recognition that there is a relationship between heat and work. Slide 3 Energy and Work, con’t. • Heat is a form of energy • Experiments of Joule • Calorimetry (see Figure 3.2) • Units of energy • The calorie , was originally defined from heat measurements • The joule is the SI unit. • One calorie = 4.184 joules Experiments of Joule showed mechanical work (turning a paddle wheel) could heat water just as an electrical heater could, showing the connection between heat and work. An earlier idea viewed heat as a caloric , some substance that flowed from one body to another. The Calorie (with a capital C), a familiar term in measuring energy content of food substances, is actually one kilocalorie .
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Chapter 3, page 2 Slide 4 Energy and Work, con’t. • Internal Energy (E or U) • An inherent property of matter • Independent of any microscopic interpretation of matter, but • Interpreted in terms of kinetic and potential energy of atoms and electrons . Slide 5 Thermodynamics Studies Energy Change E (or U) • System and Surroundings • Isolated Systems (See Figure 3.1) • No exchange between system and surroundings • Closed Systems (See Figure 3.1) • Heat exchange and work exchange between system and surroundings (note book error) • Open Systems (See Figure 3.1) • Matter, as well as heat and work, can exchange between system and surroundings. The system is any portion of the universe you choose to study. It can be the earth, an individual organism, an individual cell, a test tube of reagents, or simply that part of a solution undergoing a chemical reaction. The surroundings is everything else in the universe. Slide 6 Equilibrium versus Non- equilibrium Thermodynamics • Equilibrium Thermodynamics deal with closed systems . • Biological problems deal with open systems . • While the field of non-equilibrium thermodynamics should apply to open systems, data from equilibrium thermodynamics can be useful. Equilibrium thermodynamics represent idealized conditions— where any change is carried on with the system and surroundings always in the state of equilibrium with one another. One can calculate maximum or minimum values for thermodynamic quantity changes.
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Chapter 3, page 3 Slide 7 State Functions • State of a system depends only on pressure , volume , temperature and composition of a system.
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This note was uploaded on 07/22/2011 for the course BCH 4053 taught by Professor Logan during the Spring '06 term at FSU.

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Chapter03 - BCH 4053Spring 2003Chapter 3 Lecture Notes...

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