Question

Which pair of compounds will form a buffer in aqueous solution? HCN and NaCN HCl and NaOH NaCN and NaOH HCN and HCl HCl and NaCl NaCN and KCN.

Answer 1

Concepts and reason
The concept used to solve this problem is that a buffer is formed by the combination of a weak acid and its salt of a strong acid or by the combination of a weak base and its salt of strong acid.

Fundamentals
A buffer solution is a solution that resists change in pH on addition of a strong base or a strong acid.

Buffer solutions are of 2 types:

1. Acidic buffer- This is formed by a weak acid and its salt of strong base.
2. Basic buffer- This is formed by a weak base and its salt of strong acid.

Part A
HCN and NaCN form a buffer in aqueous Solution.
Part B
HCl and NaOH don’t form a buffer in aqueous Solution.
Part C
NaOH and NaCN will not form a buffer in aqueous Solution.
Part D
HCl and HCN don’t form a buffer in aqueous Solution.
Part E
HCl and NaCl will not form a buffer in aqueous Solution.
Part F
NaCN and KCN don’t form a buffer in aqueous Solution.