Calculating the pH of a weak acid titrated with a strong b. An analytical chemis
ID: 1045323 • Letter: C
Question
Calculating the pH of a weak acid titrated with a strong b. An analytical chemist is titrating 155.0 mL of a 0.8300 M solution of nitrous acid (HNO2) with a 0.5600 M solution of NaOH. The pK, of nitrous acid is 3.35. Calculate the ph of the acid solution after the chemist has added 133.7 mL of the Na0H solution to it. Note for advanced students: you may assume the final volume equals the initial volume of the solution plus the volume of NaOH solution added. Round your answer to 2 decimal places. PH- Explanation CheckExplanation / Answer
Since the mixture is an example acidic buffer
PH = pKa +log(moled)salt /(Moles )acid
HNO2 + NaoH - - - - - > Nano2 + H2O
no of moles of HNO2 = 155x0.83=128.65
No of moles of NaOH + 133.7x.56=74.8
No of moles of salt = 74.8 & and acid left, 128.65-74.8=53.8 mol
PH =3.35+ log (74.8/53. 7)
=3.35+log(1.39)
=3.35+0.14
PH = 3.49