# II - Thanks Veterans 1 Lecture 18 Thermodynamics Thursday...

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Unformatted text preview: Thanks Veterans 1 Lecture 18 Thermodynamics Thursday November 10, 2011 Thermodynamics: Spontaneity, Entropy, and Free Energy Chapter Seventeen 2 Thanks Veterans Thanks Veterans 3 Outline Lecture 18 What is Thermodynamics? Why study thermodynamics? Think about those food labels, calories etc. Some thermodynamics definitions Entropy Free energy Enthalpy 4 Thermodynamics vs. Kinetics Thanks Veterans Thanks Veterans 5 Introductory Concepts Thermodynamics examines the relationship between heat (q) and work (w) Spontaneity is the notion of whether or not a process can take place unassisted Entropy is a measure of how energy is spread out among the particles of a system Free energy is a thermodynamic function that relates enthalpy and entropy to spontaneity, and can also be related to equilibrium constants. ∆ G = ∆ H-T ∆ S Introduction 6 Thanks Veterans 7 First Law of Thermodynamics conservation of energy For an exothermic reaction, “lost” heat from the system goes into the surroundings . two ways energy “lost” from a system converted to heat , q used to do work , w Energy conservation requires that the energy change in the system equal the heat released plus the work done. ∆ E = q + w ∆ E = ∆ H + P ∆ V ∆ E is a state function. internal energy change independent of how done Thanks Veterans 8 First Law of Thermodynamics Conclusion: You can’t win! First law of thermodynamics: Energy cannot be created or destroyed . The total energy of the universe cannot change. though you can transfer it from one place to another • ∆ E universe = 0 = ∆ E system + ∆ E surroundings Thanks Veterans 9 The Energy Tax You can’t break even! Recharging a battery with 100 kJ of useful energy will require more than 100 kJ. Every energy transition results in a “loss” of energy. conversion of energy to heat, which is “lost” by heating up the surroundings Thanks Veterans Why study thermodynamics? Ever wonder why the FDA requires food labels with calories? How about when you exercise and want to know how much fat you burn? How about the heat you get from burning natural gas? How much work can 1 litre of gasoline do? Will a reaction occur spontaneously? Thanks Veterans 10 With a knowledge of thermodynamics and by making a few calculations before embarking on a new venture, scientists and engineers can save themselves a great deal of time, money, and frustration. “To the manufacturing chemist thermodynamics gives information concerning the stability of his substances, the yield which he may hope to attain, the methods of avoiding undesirable substances, the optimum range of temperature and pressure, the proper choice of solvent.…” - from the introduction to Thermodynamics and the Free Energy of Chemical Substances by G. N. Lewis and M....
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## This note was uploaded on 11/22/2011 for the course CHEM 162 taught by Professor Siegal during the Spring '08 term at Rutgers.

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II - Thanks Veterans 1 Lecture 18 Thermodynamics Thursday...

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