Question

How do you find the moles of acid in buffer? And the moles of base needed to reach buffer capacity?

Answer 1

For a buffer:

pH = pKa + log(conjugate base / weak acid)

so, we need:

pH of a buffer, typically near the pKa value of the weak acid pair

Then

We must identify the ratio between conjugate base AND weak acid

therefore, knowing the ratio

and the total concentration of the buffer, solve for weak acid moles

Q2.

moles of base needed for each:

you will need to get the total mol concentration of buffer

so

mol of acid + mol of conjugate base = mol of buffer required

if you have mol of acid (from previous exercise)

then, simply solve for mol of conjugate base as follows

mol of conjugate base = mol of buffer required-mol of acid