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Chemistry 2000, Fall 1996, Thermodynamics Practice Problems

  1. A 10kg piece of wood (specific heat capacity tex2html_wrap_inline68 ) at tex2html_wrap_inline70 is thrown into 100kg of water (specific heat capacity tex2html_wrap_inline72 ) at tex2html_wrap_inline74 . What is the final temperature of the wood and water?
  2. Oxygen boils at tex2html_wrap_inline76 and has a latent heat of vaporization of tex2html_wrap_inline78 . 0.1kg of liquid oxygen at its boiling point is poured into a pyrex bottle (heat capacity tex2html_wrap_inline80 ) initially at tex2html_wrap_inline82 . The oxygen evaporates quickly so that little heat is lost to the surroundings during the vaporization process. What is the temperature of the bottle when all of the oxygen has evaporated?
  3. The equilibrium constant for the reaction

    displaymath84

    is tex2html_wrap_inline86 at 298K. If the standard free energy of formation of liquid water is -237.2kJ/mol, what is the standard free energy of formation of the hydroxide ion?

  4. The standard free energies of formation of solid sodium chloride and of sodium ions and chloride ions are, respectively, -384.0, -261.87 and tex2html_wrap_inline88 . Calculate tex2html_wrap_inline90 for sodium chloride. Does your calculation agree with the notion that alkali metal salts are extremely soluble in water?
  5. Use the following table to estimate the boiling point of carbon disulfide:

    tabular33

    Hint: What is tex2html_wrap_inline102 at the boiling point?

  6. Use the table of bond enthalpies to estimate the enthalpy change in the reaction

    displaymath104

    tabular57

  7. What is the acid dissociation constant of acetic acid at tex2html_wrap_inline106 ? The acid dissociation constant at tex2html_wrap_inline108 is tex2html_wrap_inline110 and the enthalpy change for the dissociation reaction is -0.34kJ/mol.

Marc Roussel
Wed Nov 13 09:14:34 MST 1996