3 g of acetic acid is added to 250 mL of 0.1 M HCl and the solution made up to 500 mL. To 20 mL of this solution, mL of 5 M NaOH is added. The pH of the solution is

Question

3 g of acetic acid is added to 250 mL of 0.1 M HCl and the solution made up to 500 mL. To 20 mL of this solution,  mL of 5 M NaOH is added. The pH of the solution is

Canvas Classes · Accepted Answer

Step 1 — Moles in 500 mL solution:
- Acetic acid:  mol
- HCl:  mol  mol

Concentrations in 500 mL:
-  M
-  M

Step 2 — Moles in 20 mL:
- :  mol
- :  mol

Step 3 — NaOH added (0.5 mL of 5M):
Moles NaOH =  mol

NaOH first neutralises HCl:  mol
Remaining NaOH =  mol  reacts with

After reaction:
-  remaining =  mol
-  formed =  mol

Step 4 — Henderson-Hasselbalch:

Answer: 5.22

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