Chemistry 2720, Fall 96, Assignment 2

Due: November 5

All questions are equally weighted. Note that you can use any equations presented in class or in the textbook without rederiving it.

1. What is the pH of a 2mol/L solution of acetic acid in water at 298K?
2. In active transport, a reaction with a large negative free energy change is used to drive a nonspontaneous transport process. The reverse is also possible: Spontaneous flow down a concentration gradient can be used to drive nonspontaneous chemical reactions. This is called flow-coupled synthesis. For example, suppose that a cell somehow creates and maintains a proton gradient such that . (Such a gradient can only be maintained by active transport. Wheels within wheels within wheels...) This proton gradient is used to drive the synthesis of 3-phosphoglycerate (PG):

   

   For this reaction, at 298K. What is the maximum ratio of PG to glycerol which can be maintained in a single-cell organism living at by coupling the spontaneous inward flow of protons to the synthesis of PG if the phosphate activity in the cell is ?

3. What is the melting point of tin in a vacuum? At 1atm, tin melts at . The densities of solid and liquid tin are, respectively, 7.18 and 6.99kg/L. The enthalpy of melting is 60.7kJ/kg at the normal melting point. Hint: A crucial piece of data can be derived from the equilibrium condition.
4. The enthalpy of vaporization of toluene at its normal boiling point of (at 1atm) is 33kJ/mol. Calculate the boiling point of toluene in Lethbridge where the atmospheric pressure is generally about 0.89atm.
5. Relate the formula

   

   to Le Chatelier's principle. Consider both endothermic and exothermic reactions.