Applications of Aqueous Equilibrium (Show work and Answer)

Question

Calculate the pH of a buffer system made up of 0.15 M CH₃NH₂ and 0.35 M CH₃NH₃Cl

K_b = 4.4 E^-4

Answer 1

Buffers:

Use of Henderson Hasselbalch equation...

pOH = pKb + [ conj.acid]/[base]

pKb = -log 4.4x10-4 = 3.36

pOH = 3.36 + log (0.35/0.15) = 3.36 + 0.37

pOH = 3.73

pH = 14 - 3.73

pH = 10.27 = 10.3