<u>Answer:</u> The volume of NaOH that must be added is 32.3 mL
<u>Explanation:</u>
Let us assume that volume of NaOH required is 'V' mL
To calculate the millimoles of NaOH, we use the equation:
Molarity of NaOH solution = 0.1 M
Volume of solution = V mL
Putting values in above equation, we get:
Molarity of HCOOH solution = 0.1 M
Volume of solution = 50 mL
Putting values in above equation, we get:
The chemical equation for the reaction of formic acid and sodium hydroxide follows:
Initial: 5 0.1V
Final: 5 - 0.1 V - 0.1V -
- To calculate the of acid, we use the equation:
where,
= acid dissociation constant =
Putting values in above equation, we get:
- To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:
We are given:
[HCOONa] = 0.1V
[HCOOH] = 5 - 0.1V
pH = 4.0
Putting values in above equation, we get:
Hence, the volume of NaOH that must be added is 32.3 mL