ATI TEAS (Test of Essential Academic Skills) Version 7ScienceMedium
A technician is preparing a solution for an experiment that requires a pH of 7.4. They have a weak acid and its conjugate base available. To create a stable solution that resists changes in pH upon addition of small amounts of acid or base, which type of solution should they prepare?
- AA saturated solution
- BA dilute solution
- CA buffered solution
- DA supersaturated solution
Show answer & explanationAnswer & explanation
Correct answer: C. A buffered solution
A buffered solution (buffer) is a mixture of a weak acid and its conjugate base (or a weak base and its conjugate acid) that resists changes in pH when small amounts of acid or base are added. This property makes them ideal for maintaining a stable pH, as required in many biological and chemical experiments.
Why the other options are wrong
- A. A saturated solution contains the maximum amount of solute that can be dissolved at a given temperature, not related to pH stability.
- B. A dilute solution simply means a low concentration of solute; it does not inherently provide pH stability.
- D. A supersaturated solution contains more solute than a saturated solution, which is unstable and not related to pH stability.
Buffered Solution (Buffer)
A solution containing a weak acid and its conjugate base (or a weak base and its conjugate acid) that resists changes in pH upon the addition of small amounts of strong acid or base.
- Maintains a relatively constant pH.
- Crucial in biological systems (e.g., blood pH).
- Works by neutralizing added H+ or OH- ions.
Memory trick: Buffers Balance pH, Best for Bio.