A buffer is a mixed solution of a weak acid or base, combined with its conjugate
ID: 1057137 • Letter: A
Question
A buffer is a mixed solution of a weak acid or base, combined with its conjugate Note that this can be understood essentially as a common-ion problem: The conjugate is a common ion added to an equilibrium system of a weak acid or base. The addition of the conjugate shifts the equilibrium of the system to relievo the stress of the added concentration of the common ion. In a solution consisting of a weak acid or base, the equilibrium shift also results in a pH shift of the system. It is the presence of the common ion in the system that results in buffering behavior because both added H^+ or OH^- ions can be neutralized. What is the pH change of a 0.250 M solution of citric acid (pK_a = 4.77) if citrate is added to a concentration of 0.125 M with no change in volume? Express the difference in pH numerically to two decimal places.Explanation / Answer
PH = PKa + log[citrate]/[citric acid]
= 4.77+ log0.125/0.25
= 4.77 -0.3010 = 4.469 >>> answer
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.