How much NaOH to raise pH to 4? | Buffer Calculation Tutorial

In this video, we solve a classic buffer problem using the Henderson–Hasselbalch equation: What volume of NaOH must be added to acetic acid to raise the pH to 4 at 25°C? This walkthrough shows every algebra step, how to use pKa, how to set up the base/acid ratio, and how to convert moles to volume using molarity. 🔍 What you’ll learn How to use the Henderson–Hasselbalch equation How to calculate the base/acid ratio from pH and pKa How to find moles of acetic acid (HA) from volume and molarity How adding NaOH converts HA to A⁻ (sodium acetate) How to set up and solve two equations for acid and base How to check your ratio and pH How to convert moles of NaOH to volume using molarity Why this matters This type of buffer calculation appears in: CBSE Class 11/12 Chemistry JAMB Chemistry NEET/JEE foundation AP Chemistry General Chemistry (CHM 101/111) Understanding how pH, pKa, and the base/acid ratio connect is essential for buffer design and acid–base equilibrium.