you have acetic acid in a solution and then add sodium acetate

[thebillsfan]

why will the pH increase? I know sodium acetate is a base. but doesnt the system get buffered so that for every proton that the acetate ion grabs, another is dissociated by the acetic acid? i could see how itd be a solubility issue re: the common ion effect but the acetate ion is transformed into acetic acid just as acetic acid is transformed into acetate ion....so the ion concentration is the same. im just confused on this one

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[loveoforganic]

You have protons in solution, and you're adding a base. Disregard that it's the conjugate base. Base added to acidic solution means increasing pH. When you start off with an unbuffered solution and go to a buffered solution, this effect is significant. When you start off with a buffered solution, this effect is generally insignificant, but it's still present.

pH = pKa + log[A-]/[HA]

As [A-] increases, the pH of the buffer increases.