Question

Select the statement that incorrectly describes the properties of buffers: (a) The percent dissociation of a weak acid decreases in the presence of its conjugate base. (b) If a strong acid reacts with any weak base it could generate a buffer. (C) If1 L of a buffer solution is prepared containing 1M HF and 1M NaF, then pH = pka. (d) If 1.00 mol NH₃ reacts with 0.500 mol HSO3 a buffered solution is produced. (e) Buffers can be made by partially reacting a weak acid with a strong base.

Answer 1

The incorrect statement about the properties of buffers is that a buffer could be generated from the reaction of a strong acid with any weak base. Buffers are made of a weak acid and its conjugate base or a weak base and its conjugate acid, which can resist pH changes when a strong acid or base is added. Hence, the correct answer is option (b).

Step-by-step explanation:

The statement that incorrectly describes the properties of buffers is (b) If a strong acid reacts with any weak base it could generate a buffer. A buffer consists of a weak acid and its conjugate base or a weak base and its conjugate acid. A strong acid would fully dissociate in water, not providing the necessary equilibrium between the weak acid/base and its conjugate needed to buffer the solution. Buffers resist changes in pH upon the addition of small amounts of strong acids or bases due to the common ion effect and the establishment of an equilibrium between the conjugate acid-base pair.

When the concentration of the buffering system is increased, the buffer capacity is also increased. This means more strong acid or base can be neutralized before the pH changes significantly. Additionally, it's important that the components of the buffer are chosen so that the mixture's pH is close to the desired pH; this is often near the pKa of the weak acid used.