Question

Determine if each of the following combinations result in a buffer or not:

a. 0.1 M HCl/0/1 M NaCl
b. 0.1 M HCl/0.1 M NaOH
c. 0.1 M HCN/0.03 M NaOH
d. 0.1 M HCN/0.03 M HCl
e. 0.1 M HCN/0.1 M NaCN

Answer 1

Buffer solutions consist of a weak acid and its conjugate base, or vice versa. Out of the combinations provided, only 0.1 M HCN/0.1 M NaCN is a true buffer. The others do not form buffer systems because they include strong acids or bases, or fail to pair a weak acid with its conjugate base.

Step-by-step explanation:

To determine if the given combinations result in a buffer solution, we need to understand what constitutes a buffer. A buffer usually consists of a weak acid and its conjugate base or a weak base and its conjugate acid. This ensures that the addition of small amounts of acid or base does not significantly change the pH of the solution.

1. 0.1 M HCl/0.1 M NaCl: This is not a buffer because HCl is a strong acid, and NaCl is its salt, which does not provide the necessary weak acid/base pair.
2. 0.1 M HCl/0.1 M NaOH: This is also not a buffer. It's simply the combination of a strong acid and a strong base, which will neutralize each other.
3. 0.1 M HCN/0.03 M NaOH: This could be a buffer if not all of the weak acid HCN is neutralized by the NaOH. However, since we do not know if the NaOH fully neutralizes the HCN, we cannot confirm without additional information.
4. 0.1 M HCN/0.03 M HCl: This is not a buffer. HCN is a weak acid, but HCl is a strong acid and does not contribute to a buffer system with HCN.
5. 0.1 M HCN/0.1 M NaCN: This is a buffer solution because it contains a weak acid (HCN) and its conjugate base (NaCN), which can absorb additions of acid or base without a significant change in pH.