Question

Question 1    :  
HA is a weak acid. Its ionization constant, K_a, is 1.2 x 10^-13. Calculate the pH of an aqueous solution with an initial NaA concentration of 0.075 M.  

Question 2    :  
We place 0.143 mol of a weak acid, HA, in enough water to produce 1.00 L of solution. The final pH of the solution is 1.28 . Calculate the ionization contant, K_a, of HA.  

Question 3    :  
We place 0.661 mol of a weak acid, HA, and 13.0 g of NaOH in enough water to produce 1.00 L of solution. The final pH of this solution is 4.31 . Calculate the ionization constant, K_a, of HA.

Answer 1

As per guidelines, solved the first one.