Question

A 1.0-l buffer solution initially contains 0.30 mol of nh3 and 0.30 mol of nh4cl what mass of the correct reagent should you add?

Answer 1

To find the mass of reagent to be added in the reaction, we need to determine the pH of the buffer. Using the following equation

pH= pKa + log ([NH3] / [NH4+])
     = 9.26 + LOG ( 0.3 / 0.3)
     = 9.26

[h+]= 5.5x10^-10 M, you need to increase that concentration for a ph of 8.6, [H+] needs to be 2.51x10^-9M

2.51x10^-9 moles - 5.5x10^10 moles = 1.96x10^-9 moles 

1.96x10^-9 x 36.45g/mole = 7.14x10^-8 g

So the mass of HCI that you should add to the reaction is 7.14x10^-8 g