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Description
Flashcards by Tanya Haywood, updated more than 1 year ago
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Created by Tanya Haywood
over 8 years ago
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| Question | Answer |
| What makes this a buffer solution? | It has approximately equal concentrations of a weak acid and its conjugate base |
| Describe two methods of preparing an ammonia/ammonium buffer | 1. Mix similar amounts of ammonia and ammonium chloride (or nitrate) solution together 2. Add half the amount of ammonia to a solution containing ammonium ions. |
| What does a buffer solution do? | It minimises change in pH on the addition of small amounts of either acid or base |
| In a buffer solution of HA and A-, what reaction would occur if acid was added? | The weak base A- would react with the added acid producing HA and water |
| This diagram represents the way a buffer system responds to the addition of a small amount of NaOH | |
| What does this diagram show? | That when acid is added to a buffer system, the acid reacts with the conjugate base and when base is added to a buffer system, this base reacts with the conjugate acid. |
| Why is pH = pKa at half equivalence? | Because the concentration of the weak acid and its conjugate base are equal and at that point log 1 = 0 |
| What is the equation you should use when calculating PH of a buffer solution | pH = pka + log ([CB]÷[A]) |
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