1. The pKa for aspirin is 3.50. 
 
• Draw the molecular structure (showing all bonds) of aspirin; tabulate clearly the hybridization, geometry, and associated bond angles for all carbon and oxygen atoms.

 
 
 
 
• Draw the molecular structure of the form of aspirin that would be prevalent at a stomach pH of 1.4.  Comment on how well this form of aspirin would be absorbed by the gastric mucosal lipid membrane.

 
 
 
 
• Draw the molecular structure of the form of aspirin that would be prevalent at a plasma pH of 7.4.
 
 
 
 
 
 
• Calculate the ratio of the two forms of aspirin present at the stomach pH.
 
 
 
 
 
 
2. Aspirin is an ester formed through a condensation reaction:
 
• Identify the part of the aspirin molecule that makes it an ester

 
 
 
 
 
• Show a condensation reaction that results in the formation of aspirin.Include the structure of the reactants and the mechanism of the reaction in your answer.

 
 
 
 
 
3. Aspirin degrades through a hydrolysis reaction
 
• Show the structures of the products expected for acidic hydrolysis of aspirin.
 
 
 
 
 
 
 
• A recent study reported an activation energy of 122.17 kJ/mole for the hydrolysis of aspirin.  Use this activation energy to determine the relative rates of hydrolysis for aspirin at temperatures of 25°C and 50°C respectively.
 
 
 
 
 
 
4. Identify what type of molecule this is and propose how it may react with the phosphate ion at a pH of 7.4. Show the structures, the mechanism, and the proposed product.