Which of the following mixtures would result in a buffered solution?

Question

when 1.0 L of each of the two solutions are mixed?
a) 0.2 M HNO3 and 0.4 M NaOH
b) 0.2 M HNO3 and 0.4 M NaNO3
c) 0.2 M HNO3 and 0.4 M HF
d) 0.2 M HNO3 and 0.4 M NaF

Answer 1

Only d will. HNO3 will react with the fluoride ion to produce HF, but since the reaction is not complete, there will be both HF and F- in solution.

a is the reaction of a strong acid and strong base, so there can be no buffer. Since HNO3 is a strong acid, its conjugate has no acid-base properties, so b cannot be a buffer. c is a weak acid with a strong acid, so no conjugate base can be generated.