Question

A 1M solution is made of each item in a pair. When would this combination create a buffer? Choose the pairs below that you could use to make a buffered solution.

a) Na2SO4/NaHSO4
b) HCOOH/NaHCOO
c) KHSO3/H_2SO3
d) HCl/NaOH

Answer 1

Formic acid and its salt, methylamine and its salt, can make a buffer solution. Hydrochloric acid and NaOH cannot.

Step-by-step explanation:

a. Formic acid (HCHO2) is a weak acid, while NaCHO2 is the salt made from the anion of the weak acid-the formate ion (CHO2). The combination of these two solutes would make a buffer solution.

b. Hydrochloric acid (HCl) is a strong acid, not a weak acid, so the combination of these two solutes would not make a buffer solution.

c. Methylamine (CH3NH2) is like ammonia with one of its hydrogen atoms substituted with a CH3 (methyl) group. Because it is not on our list of strong bases, we can assume that it is a weak base. The compound CH3NH3Cl is a salt made from that weak base, so the combination of these two solutes would make a buffer solution.

d. Ammonia (NH3) is a weak base, but NaOH is a strong base. The combination of these two solutes would not make a buffer solution.