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Edexcel A-level Chemistry Strong and weak acids

Strong and weak acids

This page covers the following topics:

1. Strong acids
2. Weak acids

Acids are solutions which act as a source of H⁺ ions. To be classified as a strong acid, the substance must completely dissociate into its ions in solution, represented by a single arrow in the reaction equation. Strong acids can be identified by their very low pH, usually below pH 1.

Strong acids

Weak acids only partially dissociate into its ions in solution, represented by a equilibrium arrow. Weak acids can be identified by their pH, usually between pH 3-5. Carboxylic acids are a great example of weak acids.

Weak acids

1

What pH range do weak acids usually fall within?

What pH range do weak acids usually fall within?

2

Identify the conjugate base in the following equation:

HNO₃ + Hβ‚‚O β‡Œ H₃O⁺ + NO₂⁻.

Identify the conjugate base in the following equation: 

HNO₃ + Hβ‚‚O β‡Œ H₃O⁺ + NO₂⁻.

3

What is the defining property of a strong acid?

What is the defining property of a strong acid?

4

Calculate the pH of 1.5 M sulphuric acid to 2 decimal places.

Calculate the pH of 1.5 M sulphuric acid to 2 decimal places.

5

What is the definition of a weak acid?

What is the definition of a weak acid?

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