Final answer:
True, effective buffers contain approximately equal amounts of a weak acid and its conjugate base, allowing them to neutralize added acids or bases without significantly changing pH.
Step-by-step explanation:
True, most buffers are indeed composed of approximately equal amounts of a weak acid and the salt of its conjugate base. A buffer's capacity to resist changes in pH is most effective when there is a 1:1 ratio of weak acid to its conjugate base, as this allows the buffer to neutralize added acids or bases effectively.
For example, an acetic acid (HC₂H₃O₂)/sodium acetate (NaC₂H₃O₂) buffer contains equal concentrations of acetic acid and sodium acetate. When a strong acid is added to this buffer, it reacts with the conjugate base, sodium acetate, shifting the equilibrium slightly without a significant change in pH. Similarly, when a strong base is added, it reacts with acetic acid, again shifting the equilibrium while maintaining the pH.