Question

A 340.0−mL buffer solution is 0.140M in HF and 0.140M in NaF.

What mass of NaOH could this buffer neutralize before the pH rises above 4.00?

Answer 1

@aaronq

Answer 2

@Somy

Answer 3

Easiest way is to use the Henderson-Hasselbalch equation

\(pH=pKa+log\dfrac{[A^-]}{[HA]}\)

Find the change to occur is \([A^-]\) consistent to that pH change.

Then use \(Molarity=\dfrac{moles_{solute}}{L_{solution}}\) to find the moles used.

These moles are equal to the moles of NaOH neutralized.

finally, use \(moles=\dfrac{mass}{Molar~mass}\) to find the mass of NaOH.

Answer 4

the change to occur IN*** \([A^-]\)