Calculate the ratio of naf to hf required to create a buffer with ph = 4.05.

Ratio of NaF to HF required to create a buffer with pH=4.15 is 8.13

Explanation:

HF is an weak acid and NaF is a strong electrolyte containing (Conjugate base of HF)

Hence mixture of NaF and HF creates a buffer systems.

Applying Henderson-Hasselbalch equation to this buffer system-

Here, species inside third bracket represents their concentrations.

It is given that pH of buffer is 4.05 and literature value suggests of HF is 3.14

Plug-in these two values in the above equation-

As 1 molecule of NaF contains 1 molecule of therefore

the volume increases