Chemistry 1410

Spring 2005

Practice problems for Chapter 15

 


  1. Predict whether solutions of the following salts will be acidic or basic.

 

        Give a reason for each answer.           Write out the relevant equilibria.

 

a.       Sodium benzoate  (  C6H5COONa ).   In the formula, the cation  ( Na+) is written after the anion ( C6H5COO- ).

 

 

 

b.      Ammonium chloride ( NH4Cl ).

 

 

 

 

c.       Potassium cyanide ( KCN ).

 

 

 

 

2. Calculate the pH of 0.250 M solution of KCN (aq). The Ka for HCN is in the notes from an example problem.

 

 

 

pH = 11.4

 

 

 

 

 

 

 

3. Calculate the pH of a 0.175 M solution of caffeine.  The Kb for caffeine is in the book.

 

 

pH = 11.9