How do you answer a questions on how a buffer solution works?

This question would be a 5/6 mark question- marks are displayed throughout

You always start by defining what a buffer solution is: A buffer solution is a system that minimises a change in pH on the addition of a small amount of acid or a base. (1) Then you would write out the equilibrium of the buffer solution, for example, CH3COOH (=) CH3COO+ H+ (2). The conjugate base in this solution is CH3COOand the weak acid is the CH3COOH.

Then you would explain the effect of adding a small amount of acid to the buffer solution:

The conjugate base (CH3COO-) removes the added acid. When an acid is added the [H+] increases and these Hreact with the conjugate base (3). The equilibrium shifts to the left (4), removing most of the Hions.

The weak acid (CH3COOH) removes the added alkali. When an alkali is added the [OH-] increases. The small amount of Hpresent reacts with the OHto form H2O (5). The weak acid dissociates, causing the equilibrium to shift to the right (6) to restore most of the H+ ions. 

I would the attach an example exam question which they can complete. 

AR
Answered by Alice R. Chemistry tutor

3699 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

Explain why benzene requires use of a halogen carrier catalyst to react with bromine while phenol does not.


Explain why silicon dioxide has a higher melting point than sulphur trioxide


A sample of nitrogen gas is heated to 100°C, at a pressure of 10kPa and volume of 0.2m^3. How many moles of gas are present?


Explain why compounds of Fe^2+ are coloured in solution. (4 marks)


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning