help pls

calculate the amount of acetic acid and acetate needed to prepare the acetate buffer system, two liters of 5 mM buffer solution with pH 5.2. pKa of acetate buffer is 4.76.

Question

help pls

calculate the amount of acetic acid and acetate needed to prepare the acetate buffer system, two liters of 5 mM buffer solution with pH 5.2. pKa of acetate buffer is 4.76.

aaronq · Answer

so start with the Henderson Hasselbalch equation

$pH=pKa+ log\dfrac{[AcCOO^-]}{[AcCOOH]}$

plug your values in and find the $\dfrac{[AcCOO^-]}{[AcCOOH]}$ ratio.

From there you can find the necessary amounts (moles) in your 2 L system.

anonymous · Answer

@aaronq does the ratio only apply for 1 L?

aaronq · Answer

well the ratio is in terms of concentration, so you wanna find the total moles first, then find how much there is of each with the ratio.

anonymous · Answer

im confused

aaronq · Answer

whats the total amount of moles of the buffer?

anonymous · Answer

0.005 M?

aaronq · Answer

that's the molarity, what about moles?

anonymous · Answer

@aaronq how to get the moles out from that?

aaronq · Answer

use the molarity formula and the volume of the solution