A buffer solution was made up of ammonia and water which produced ammonium ions and hydroxide ions. 

a. Write the equilibrium equation which represents this buffer and the simplified Ka expression 

b. Write an equation which shows ammonium breaking into its constituents. Calculate the initial pH and the pKa of this buffer solution knowing that the solution initially contained 1.00 M of ammonia and 0.400 M of ammonium chloride. (Ka = 5.62 ×10-10 M) 

c. Calculate the effect on the pH of adding 

(i) 7.00 cm3 of 10.0 M hydrochloric acid and

 (ii) 9.00 cm3 of 10.0 M sodium hydroxide solution to 1000 cm3 of the buffer solution.