CAIE A Level Chemistry 9701 · Equilibria
A student wants to prepare a buffer solution with a pH close to 9.2 using aqueous ammonia, , and solid ammonium chloride, .
Suggest how the student could make this buffer solution and explain how it controls pH when small amounts of acid or alkali are added. Include chemical equations in your answer.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Suggest means: Apply what you know to an unfamiliar situation. There may be more than one acceptable answer. Reason from the principle you have learned to the new context, and say which principle you are using.
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