Question detail
Which of the following pairs would form a basic buffer solution?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Acids and bases (A-level only)
Question
- A. NH3 and NH4Cl
- B. HCl and NaCl
- C. NaOH and H2O
- D. CH3COOH and NaCH3COO
Answer
NH3 and NH4Cl
Explanation
A basic buffer solution can be formed from a weak base, such as ammonia (NH3), and its conjugate acid, ammonium chloride (NH4Cl). This combination allows the solution to resist changes in pH.
Common mistake
Misunderstanding Buffer Action
Students often confuse how basic buffers resist pH change by thinking they only neutralize acids without considering the equilibrium involved.
To explain how basic buffers resist pH change, remember that they consist of a weak base and its conjugate acid. When an acid is added, the weak base reacts with the hydrogen ions, minimizing pH change. For example, in a buffer solution of ammonia (NH3) and ammonium chloride (NH4Cl), the reaction can be represented as: NH3 + H+ ⇌ NH4+. This shows how the weak base (NH3) reacts with added H+ ions, maintaining the pH.
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