Class 11 Chemistry simulations · Equilibrium

Buffer solutions (Henderson equation)

Mix acetic acid with sodium acetate and add a little strong acid or base; see how little the pH changes.

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What to notice

A buffer resists pH change because added H⁺ is taken up by A⁻ and added OH⁻ by HA.

Key relation

pH = pKₐ + log([A⁻]/[HA]) ; pKₐ(acetic acid) = 4.76

Try this

Add 0.01 mol of HCl to the buffer and to pure water. Compare the pH changes.

What you can change

• Acetic acid: 0.01 to 0.2 mol
• Sodium acetate: 0.01 to 0.2 mol
• Strong acid (+) / base (−) added: -0.05 to 0.05 mol

More in Equilibrium

• Le Chatelier’s principle (Haber process)
• pH of acids and bases
• Solubility product and common ion effect

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