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What is thermodynamics?

What is thermodynamics?. Muscular Energy. Kinetic Energy. C. H. O. H. 2. O. H. O. H. H. H. O. H. H. H. O. H. O. H. Glucose. Chemical Energy. Muscular Energy. Solar Energy. Chemical Energy. Big Bang. H 2. Nuclear Fusion. Sunlight. Plant. Food. Energy. Fun.

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What is thermodynamics?

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  1. What is thermodynamics? Chapter 1

  2. Muscular Energy Kinetic Energy Chapter 1

  3. C H O H 2 O H O H H H O H H H O H O H Glucose Chemical Energy Muscular Energy Chapter 1

  4. Solar Energy Chemical Energy Chapter 1

  5. Big Bang H2 Nuclear Fusion Sunlight Plant Food Energy Fun Chapter 1

  6. What is thermodynamics? • The word thermo-dynamic was first used by Kelvin in 1849. • Today we define thermodynamics as the science that deals with the interconversion of heat and work and all its applications. Chapter 1

  7. Highlights in thermodynamics • Black (1760-1766), calorimetry • Mayer and Joule (1842-1852), interconversion of heat and work • Kelvin (1848-1849), absolute temperature scale (K) • Clausius (1850), second law • Kelvin (1851), second law, dissipation of energy • Clausius (1854-1865), concept of entropy • Gibbs (1873), chemical thermodynamics • Gibbs (1876-1878), chemical potential, phase rule • Helmholtz (1882), equilibrium, free and bound energy • Van’t Hoff (1884-1887), equilibrium constant, solutions • Nernst (1906), heat theorem (third law) • Simon (1927), improved version of third law Chapter 1

  8. Important Concepts • System: any designated volume of space. • Surroundings: everything else in the universe. Chapter 1

  9. Important Concepts • State: a collection of all measurable macroscopic properties (variables) of a system. • State function: any property that depends only on the state variables. All state variables are also state functions. Is work a state function? Chapter 1

  10. Important Concepts • Intensive property: non-additive properties of a system. E.g. pressure, temperature • Extensive property: additive properties of a system. E.g. volume, energy A state variable or function is also an intensive property. Chapter 1

  11. Equations of State • A relationship between several state variables of a system. • E.g. the ideal gas law PV = nRT Remember this equation. Chapter 1

  12. Important Concepts • Constraint: variables that are not allowed to change during a process. • Equilibrium: A system is at equilibrium if its state does not change with time. When a system is in equilibrium with its surroundings, it has unconstrained variables which are neither changing nor causing any changes in the surroundings. Chapter 1

  13. Temperature is An intensive property A state variable A state function All of the above An intensive property A state variable A state function Temperature, Heat and Thermometers Heat is • An extensive property • An interaction between two systems • A form of energy Chapter 1

  14. Absolute Temperature Scale • According to the ideal gas law PV = nRT If we graph PV against T, we have That makes me the absolute zero. PV Chapter 1 T

  15. All thermodynamic equations are written in terms of the absolute temperature scale T K = T ºC + 273.15 Chapter 1

  16. A process is A way to cause a change in a system Defined by the beginning and end states of the system A reversible process is One during which the system is constantly in equilibrium with its surroundings. Processes Real processes are never reversible. Chapter 1

  17. Isothermal Constant temperature during entire process Closed Nothing goes into or out of the system. Processes adiabatic • No heat flow during entire process Isolated • No interaction with its environment in any way I only reject heat. I reject everything! Chapter 1

  18. Calculations in SI Units n R T P = V (moles) (8.314 JK-1 mol-1) (Kelvin) (m3) (Pascals) Check out Appendix D! Stick with SI units. Make fewer errors. Chapter 1

  19. Sign Convention All quantities are expressed relative to the system, not to the surroundings. Disagree! + - Chapter 1

  20. Specific vs Total Quantities • V: non-specific volume • V: mole-specific volume, or molar specific volume, volume based on unit mole • V: mass-specific volume, volume based on unit mass ~ Chapter 1

  21. Example 1.3 The molar specific heat capacity (Cp) of lead is 26.4 JK-1 mol-1. What is the heat capacity of 1 gram lead? 26.4 JK-1 mol-1 Cp = ________________= 0.127 JK-1 g-1 207.2 g/mol ~ Know how to convert between specific and total quantities. Chapter 1

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