What components make up a basic buffer?

A weak base and its conjugate acid (typically as a salt).

Explain how an acidic buffer responds when hydrogen ions are added.

The conjugate base reacts with the added H⁺ ions to form the weak acid, removing the added hydrogen ions.

Explain how an acidic buffer responds when hydroxide ions are added to it.

The added hydroxide ions react with the weak acid component of the buffer to form water and the conjugate base, thereby removing the added hydroxide ions and minimising pH change

What products are formed when hydroxide ions react with the weak acid in an acidic buffer solution?

Water and the conjugate base of the weak acid

Edexcel A-Level Chemistry 9CH0

Atomic Structure and the Periodic Table

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Redox I

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Acid-Base Equilibria

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Acid-Base Equilibria

Buffer solutions and the Henderson-Hasselbalch equation

3 things to know
Papers 1 and 3

Overview

Acidic and basic buffers and how an acidic buffer removes added H⁺ and OH⁻ ions, the Henderson–Hasselbalch equation, why pH equals pKₐ at half-equivalence so Kₐ can be read from a titration curve, and why a weak acid gives a less exothermic enthalpy of neutralisation.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

How does an acidic buffer resist a change in pH?

Key term

Define a buffer solution.

Key term

What components make up an acidic buffer?

Questions from this subtopic

Each one with the model answer underneath.

1
Define a buffer solution.
Model answer
A buffer solution is a solution that resists changes in pH when small amounts of acid or base are added.
2
What components make up an acidic buffer?
Model answer
A weak acid and its conjugate base (typically as a salt).
3
What components make up a basic buffer?
Model answer
A weak base and its conjugate acid (typically as a salt).
4
Explain how an acidic buffer responds when hydrogen ions are added.
Model answer
The conjugate base reacts with the added H⁺ ions to form the weak acid, removing the added hydrogen ions.
5
Explain how an acidic buffer responds when hydroxide ions are added to it.
Model answer
The added hydroxide ions react with the weak acid component of the buffer to form water and the conjugate base, thereby removing the added hydroxide ions and minimising pH change
6
What products are formed when hydroxide ions react with the weak acid in an acidic buffer solution?
Model answer
Water and the conjugate base of the weak acid

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