The secret to these is to recognize what you have in the solution at each addition.
The first thing you do is to determine where the equivalence point is; i.e., number of mL HCl added to get to the equivalence point.
20 mL--you have a mixture of NH3 and NH4Cl. That makes a buffer; use the Henderson-Hasselbalch equation.
60 mL is the eq point. The pH is determined by the hydrolysis of the salt NH4Cl.
0 mL you have 0.50M NH3. I'm sure you've worked many a problem like that.
Consider the titration of 30.0 mL sample
of 0.050 M NH3 with 0.025 M HCl.
Calculate the pH after the following volumes
of titrant (acid)have been added:
a)0 mL,
b)20.0mL,
c)60.0mL,
d)65mL
Kb for NH3 is 1.8 x 10^-5
1 answer
1 answer