WJEC Chemistry Practice Exam 2025 – The Complete All-in-One Guide to Exam Success!

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What does a buffer typically contain?

A strong acid and a weak base

A weak acid and its conjugate base

A buffer typically consists of a weak acid and its conjugate base. This combination is essential because it provides the system with the ability to resist changes in pH when small amounts of strong acids or strong bases are added. The weak acid can neutralize added bases, while the conjugate base can neutralize added acids.

In this system, the weak acid dissociates slightly in solution, providing some acidic protons, while the conjugate base is available to react with any excess hydrogen ions that may be introduced by a strong acid. Conversely, when a strong base is added, the weak acid can react with the hydroxide ions produced, effectively mitigating the increase in pH.

Buffers play a crucial role in various biological and chemical systems where maintaining a stable pH is vital for the proper functioning of processes like enzyme activity and metabolic reactions.

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A salt and a strong base

An oxidizing agent and a reducing agent

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