posted by Vanessa on .
Will this solution form a buffer?
100 mL of .10 M NH3; 100 mL of .15 M NH4Cl
NH3= .01 moles
NH4Cl= .015 moles
.... not sure what else to do.
I think we use the H-H equation, but I don't know how to find pKa, or even what pKa is. This should give the pH of the solution, but I don't think the pH would indicate whether or not this solution would be a buffer? How do you know if a solution is a buffer, and how do you know if the solution is not a buffer?
Yes, use the H-H equation.
Find Ka = Kw/Kb. You know Kw for water and Kb for NH3. From Ka, find pKa.
NH3 =s the base
NH4Cl is the acid. Plug into HH and solve for pH. And, yes, it's a buffer. However, do you need to solve for pH. The question is, will it form a buffer. The answer is yes. It is a solution of a weak base and its salt. A weak acid and its salt also will form a buffer.