In: Chemistry
A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3. Determine the pH of the solution after the addition of 50.0 mL of HNO3. The Kb of NH3 is 1.8 × 10-5.
no of moles of NH3 = molarity * volume in L
= 0.1*0.1 = 0.01 moles
no of moles of HNO3 = molarity * volume in L
= 0.1*0.05 = 0.005 moles
NH3 + HNO3 ---------------> NH4NO3
I 0.01 0.005 0
C -0.005 -0.005 0.005
E 0.005 0 0.005
Kb = 1.8*10^-5
PKb = -logKb = -log1.8*10^-5 = 4.75
POH = PKb + log[NH4NO3]/[NH3]
= 4.75 + log0.005/0.005
= 4.75 +0
= 4.75
PH = 14-POH
= 14-4.75 = 9.25