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Chapter 7:  Thermodynamics

Chapter Learning Goals:

  1. You know several definitions: 
    • Energy:  the capacity to do work.
    • Work:  Action of a force through a distance.
    • Heat:  energy transferred between a system and its surroundings due to temperature differences.
  2. You know defitions for potential energy and kinetic energy.
  3. You know that thermal energy is associated with the kinetic energy of molecules in a system.
  4. You can calculate the quantity of heat transfered between substances if given masses, specific heats and the temperature changes.
  5. You can predict ΔT for heat transfer between substances given masses, specific heats and initial temperatures.
  6. You know the First Law of Thermodynamics:  energy is neither created nor destroyed, so the energy of an isolated system is constant.
  7. You recognize that a change in an isolated system can manifest as either work (w) or heat (q), and that ΔU = q + w.  For an isolated system, the First Law says ΔUisolated system = 0, so for any change, w = -q.
  8. For systems interacting with their surroundings, you know sign conventions:  if heat is absorbed by the system, q > 0; if heat is given off, q < 0.  if work is done on the system, w > 0; if work is done by the system on the surroundings, w < 0.
  9. You understand that if we control a system to maintain a constant volume, no work is done in any change and thus ΔUsystem = qV.  An example is a reaction performed in a sealed bomb calorimeter.
  10. You know how to define enthalpy H = U + PV, and can articulate why ΔH = qP for a process at constant temperature and pressure.
  11. You recognize that changes of state are accompanied by specific molar ethalpies:  ΔHv for vaporization/condensation, ΔHm for melting/freezing.  You know the signs expected for these values.
  12. You can use Hess's Law to arrive at a net ΔHº given a sequence of processes with known ΔHº that get from the initial state to the final state.
  13. You know that the ΔHfº for any element in its standard state is 0, and serves as a reference for comparing ΔHfº for any chemical compound.
  14. You can calculate the standard enthalpy of reaction for any chemical transformation, if given the standard enthalpy of formation for each reactant and each product.

Links:

Brownian motion of nanoparticles (YouTube)

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