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Chemistry 2720 Spring 1998 Assignment 2

Due: Friday, March 6, noon.

General note: You may need to review your first-year chemistry notes to complete this assignment.

  1. Under standard conditions, the isomerization of D-glucose-6-phosphate to D-fructose-6-phosphate has a tex2html_wrap_inline66 of 1.7kJ/mol at tex2html_wrap_inline68 . Give an example of conditions under which this reaction would be spontaneous. [5 marks]
  2. Alcoholic fermentation is used by some organisms to produce energy storage compounds which in turn are used to generate useful work. The final reaction in the fermentation pathway is

    displaymath70

    All substances in this reaction are in aqueous phase. Suppose that in a certain cell, this reaction is used directly in the production of work. The concentrations of acetaldehyde, NADH, ethanol and tex2html_wrap_inline72 are, respectively, 2mM, tex2html_wrap_inline74 , tex2html_wrap_inline76 and tex2html_wrap_inline78 . The pH is 6.2. The standard free energy change for this reaction in the biochemists' standard state is tex2html_wrap_inline80 at 298K. How much non-PV work can be extracted from this reaction at 298K per mole of ethanol produced? [5 marks]

  3. Calculate the concentrations of all phosphates species in a pH 11.5 buffer at 298K in which the total concentration of phosphates is 0.01mol/L. [10 marks]

    Hint: After finding the tex2html_wrap_inline82 's, figure out which species will be present in large quantities in the solution.

  4. What is the pH of a tex2html_wrap_inline84 solution of HCl in water at 298K? [5 marks]

    Hint: The tex2html_wrap_inline82 of HCl is not required to do this calculation, but it's also not quite as easy as it looks.

  5. Two fluids have an enthalpy of mixing of 5.2kJ/mol at tex2html_wrap_inline88 . Will they mix well at this temperature? [5 marks]

Marc Roussel
Wed Mar 11 11:53:07 MST 1998