Which of the following when added to 100.0mL of a 0.100M soln of NH4Cl would produce a buffer soln?
a.100.0mL of 0.100 M HCl soln
b. 100.0mL of 0.050M NaOH soln
c. 100.0mL of 0.100M NaOH soln
d. 100.0mL of 0.050M NH4No3 soln
e.none of the above
To be a buffered solution, what must we have? We must have a weak acid and its salt OR a weak base and its salt.
I don't see anything there that is a weak acid or base and its salt.
a is a strong acid.
b is a strong base.
c is a strong base (just a different concn).
d is the salt of a weak base and a strong acid and in a very limited set of circumstances MIGHT work. Generall, however, no.
To determine if a solution will form a buffer with a given solution, we need to check if the two solutions contain a weak acid and its conjugate base, or a weak base and its conjugate acid.
In this case, we have NH4Cl, which is a salt of the weak acid NH4OH (ammonium hydroxide) and the strong acid HCl. Therefore, to form a buffer solution, we need to add a solution that contains NH4OH or its conjugate base NH3.
Let's examine each option:
a. 100.0mL of 0.100 M HCl solution:
HCl is a strong acid, not a weak acid or its conjugate base. Therefore, this solution will not form a buffer.
b. 100.0mL of 0.050M NaOH solution:
NaOH is a strong base, not a weak base or its conjugate acid. Therefore, this solution will not form a buffer.
c. 100.0mL of 0.100M NaOH solution:
Similar to option b, NaOH is a strong base and will not form a buffer.
d. 100.0mL of 0.050M NH4NO3 solution:
NH4NO3 is a salt of NH4OH, and NH4OH is the weak acid needed for a buffer. Therefore, adding this solution will form a buffer.
e. None of the above:
Since option d meets the requirement for forming a buffer solution, option e is not correct.
Therefore, the answer is option d. Adding 100.0mL of 0.050M NH4NO3 solution to 100.0mL of a 0.100M solution of NH4Cl will produce a buffer solution.