Question

The buffer solution is
a) NaCl/HCl
b) HCOOH/HCOOK
c) K₂SO₄/H₂SO₄
d) NH₄OH/KOH

Answer 1

Buffer solution is that solution that resist the change of pH.  It either has the weak acid and its salt with the strong base. This is called acidic buffer. While the basic buffer is formed by weak base and its salt with strong acid.

In the given problem, option b is the buffer solution.

HCOOH (formic acid)

HCOOK (potassium salt of formic acid)

HCOOH ⇒ HCOO ⁻ + H⁺

by addition of small acid, H⁺ ion combines with that acid and maintains the pH.

By addition of small base, H⁺ combines with OH⁻ to form H₂O.