Chemistry 2720 Fall 1999 Test 2

Answer all questions. Note that useful information (data, equations) is given at the end of this paper.

Aids allowed: calculator.

1. The solubility of lead (II) chromate ( ) in water at 298K is . Calculate the standard free energy of formation of lead chromate. [10 marks]
2. Estimate the boiling point of . [10 marks]
3. A sample of 25g of sodium acetate ( , molar mass 82.03g/mol) is dissolved in 1L of water at . What is the pH of the solution? The base ionization constant ( ) of acetate at this temperature is . [10 marks]

   Hint: is defined in the information section.

4. The synthesis of glucose-6-phosphate (G6P) is a key step in the biological oxidation of glucose:

   

   This reaction is coupled to ATP hydrolysis:

   

   All data given above correspond to reactions in aqueous solution at 298.15K. What is the minimum ratio of ATP to ADP required to maintain a G6P:glucose ratio of 1000? [10 marks]

   Hint: Imagine that conditions are initially such that and that the ATP to ADP ratio starts to drop. At what point does the production of G6P cease to be spontaneous?

5. Suppose that you are teaching a thermodynamics course. On one of your tests, you ask the following question:

   Calculate the maximum non-PV work which can be obtained from the reaction

   

   per mole of A reacted at 350K when the partial pressures of A and B are, respectively, 0.2 and 0.5atm. For this reaction, and at 298.15K.

   One student's solution goes as follows:

   

   Since the reaction involves two equivalents of A,

   

   Identify and briefly explain the errors in the student's solution. Refer to steps of the student's solution by number. [10 marks]

Useful information

The autoionization constant of water ( ) at 298.15K is .

The base ionization constant is the equilibrium constant for the reaction

To convert degrees Celsius to Kelvin, add 273.15.

Standard thermodynamic data at 298.15K