I need to figure out how to calculate the change in pH when 6.00 mL of .100 M HCl (aq) is added to a 100 mL of a buffer solution that is .10 M in NH3 (aq) and .10 M in NH4Cl (aq). Also I need to calculate the change in pH when 6.00 mL of 0.10 M Na)H (aq) is added to the original buffer solution. I have tried several ways to do this and haven't gotten in correct so explanation of steps would be great. Thanks