You need to produce a buffer solution that has a pH of 5.08. You already have a solution that contains 10 mmol (millimoles) of acetic acid. How many millimoles of acetate (the conjugate base of acetic acid) will you need to add to this solution? The of acetic acid is 4.74.
you ffing moron @DrBob222
To solve this problem, we need to use the Henderson-Hasselbalch equation, which relates the pH of a buffer solution to the pKa (negative logarithm of the acid dissociation constant) of the weak acid and the ratio of the concentration of the conjugate base to the weak acid in the buffer solution.
The Henderson-Hasselbalch equation is given as:
pH = pKa + log([A-]/[HA])
Where:
pH = desired pH of the buffer solution
pKa = pKa value of the weak acid
[A-] = concentration of the conjugate base
[HA] = concentration of the weak acid
In this case, the weak acid is acetic acid (CH3COOH) and its pKa is given as 4.74. We want a pH of 5.08, so we can plug these values into the Henderson-Hasselbalch equation and solve for [A-].
5.08 = 4.74 + log([A-]/[10 mmol])
Next, rearrange the equation to isolate [A-]:
log([A-]/[10 mmol]) = 5.08 - 4.74
log([A-]/[10 mmol]) = 0.34
Now, convert the equation into exponential form:
10^(0.34) = [A-]/[10 mmol]
[A-] = 10^(0.34) * [10 mmol]
Calculate [A-]:
[A-] = 2.24 * [10 mmol]
[A-] = 22.4 mmol
Therefore, you will need to add 22.4 millimoles of acetate (the conjugate base of acetic acid) to the solution to produce a buffer solution with a pH of 5.08.