Question

A buffer is prepared using 0.28 M HNO2 and 0.23 M NO2 − . The pKa for HNO2 is 3.34. What is the pH of

this buffer after the addition of 0.05 M HCl?

Answer 1

$pH = pKa + log10([A-]/[HA])$

= 3.34 + log (0.33/0.23)

= 3.34+ 0.2= 3.54