What mass of ammonium nitrate must be added to 350 mL OF 0.150 M solution of ammonia to give a buffer having pH of 9.00? (Kb(NH3)= 1.8X10-5

Answer 1

pH = pKa + log (base)/(acid)
9.00 = pKa + log b/a
You get pKa from Kb. Convert Kb to pKb; then pKa + pKb = 14 and solve for pKa.
Substitute (base) from the problem and solve for (acid), then convert (acid) to grams NH4NO3. Post your work if you get stuck.

Answer 2

I got 2.36g. Is that correct?