Buffer Solutions – Complete Guide for NEET, JEE & Boards 2026

Buffer Solutions are one of the most scoring yet concept-heavy topics of Physical Chemistry (Ionic Equilibrium). This page by CHEMASH is designed as a one-stop doubt-clearing resource for Class 11, Class 12, NEET, JEE Main, JEE Advanced and CUET 2026.

If you truly understand buffer solutions, you automatically master: pH, pKa, pKb, Henderson equation, biological chemistry and numerical problem-solving.

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Table of Contents

• What is a Buffer Solution?
• Why Buffer Solutions are Important?
• Types of Buffer Solutions
• Acidic Buffer Solutions
• Basic Buffer Solutions
• Mechanism of Buffer Action
• Henderson–Hasselbalch Equation
• Buffer Capacity
• Numerical Problems (NEET/JEE)
• Applications of Buffer Solutions
• Exam Perspective 2026
• MCQs
• Quiz & Fill in the Blanks
• FAQs
• Why Trust CHEMASH?

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What is a Buffer Solution?

A buffer solution is a solution that resists change in its pH when:

• a small amount of acid is added
• a small amount of base is added
• the solution is diluted

According to NCERT, buffer solutions work because of the equilibrium established between a weak acid/base and its conjugate salt.

Important: Buffers do NOT keep pH constant forever. They work only within a specific pH range.

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Why Buffer Solutions are Important?

Life without buffers is impossible. Even a slight pH change can destroy chemical systems.

• Human blood must stay near pH 7.4
• Enzymes work only in narrow pH ranges
• Drugs require controlled pH for stability
• Industries need fixed pH for reactions

Chemash Insight: In exams, questions often test why buffers are required more than definitions.

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Types of Buffer Solutions

1️⃣ Acidic Buffer Solutions

An acidic buffer is made by mixing:

• a weak acid
• its salt with a strong base

Example:

CH₃COOH + CH₃COONa

pH of acidic buffer is always less than 7.

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2️⃣ Basic Buffer Solutions

A basic buffer is made by mixing:

• a weak base
• its salt with a strong acid

Example:

NH₄OH + NH₄Cl

pH of basic buffer is always greater than 7.

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Mechanism of Buffer Action (VERY IMPORTANT)

Acidic Buffer Mechanism

CH₃COOH ⇌ H⁺ + CH₃COO⁻

• Added acid → neutralized by CH₃COO⁻
• Added base → reacts with CH₃COOH

Result: pH change is minimum.

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Henderson–Hasselbalch Equation

pH = pKa + log ( [Salt] / [Acid] )

This equation is the heart of buffer numericals.

Chemash Exam Tip: If salt concentration = acid concentration → pH = pKa

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Buffer Capacity

Buffer capacity is the ability of a buffer to resist pH change.

• High concentration → high buffer capacity
• Equal salt & acid → maximum efficiency

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Numerical Problems (NEET/JEE Level)

Q. Calculate pH of buffer containing 0.1 M CH₃COOH and 0.1 M CH₃COONa. pKa = 4.76

pH = 4.76 + log(0.1/0.1)
pH = 4.76

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Applications of Buffer Solutions

• Blood pH regulation
• Pharmaceutical formulations
• Food preservation
• Fermentation industry
• Analytical chemistry

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Exam Perspective 2026 (VERY IMPORTANT)

• 1–2 questions guaranteed in NEET
• Numerical based in JEE Main
• Conceptual MCQs in Boards

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MCQs

Q. Which system acts as buffer?

CH₃COOH + CH₃COONa ✅

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Quiz & Fill in the Blanks

1. Buffer resists change in ____.

Answer: pH

2. pH = pKa when ____ = ____.

Answer: salt, acid

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FAQs

Does dilution affect buffer pH?

No, ratio remains same.

Can strong acids form buffers?

No.

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Related: Ionic Equilibrium | Chemical Equilibrium | Britannica | LibreTexts