Question

What is the pH of a solution containing 0.049 M of formic acid and 0.055 M of sodium formate?

Answer 1

pH of solution is 3.80

Step-by-step explanation:

• Formic acid an weak acid and formate is conjugate base of formic acid
• Hence solution containing formic acid and formate acts as a buffer.
• According to Henderson-Hasselbalch equation for a buffer consist of an weak acid (formic acid) and it's conjugate base (formate)-

`pH=pK_(a)(formic acid)+log((C_(formate))/(C_(formic acid)))`

where, C stands for concentration

• 
  `pK_(a)` of formic acid 3.75

So,
`pH=3.75+log((0.055)/(0.049))=3.80`