Buffer Calculation Help

Can anyone help me with finding out the mass in buffer calculations when your given the pH and one concentration?! I'm doing OCR salters

Reply 1

Borek

Use Henderson-Hasselbalch equation to calculate the other concentration, then calculate number of moles from the volume and concentration, then convert number of moles to mass using molar mass.

Reply 2

livvs

H2PO4- --> H+ + HPO42- equation 5.1

Ka = 6.2 × 10–8 mol dm–3

A student prepared 1.0dm3 of a pH 7.0 buffer solution based on the system shown in
equation 5.1.
The solution was prepared by dissolving Na2HPO4 and NaH2PO4 in deionised water.
The concentration of Na2HPO4 in the prepared buffer solution was 0.10moldm–3.
Calculate the mass of solid NaH2PO4 (Mr 120) that the student used in preparing this buffersolution.

Can I use that for this?