Notes on Quiz 5 : Please have a look at the past quizzes. 1. You should be able to get the pH of solutions of single salts, like question 3 in Quiz 4: split the salt completely into ions, consider which ion is going to be acidic or basic, write the corresponding equilibrium etc. 2. Buffer solutions: either a mixture of weak conjugate acid/base pair or a mixture obtained by partial neutralization of weak acid with strong base or weak base with strong acid, with weak component in excess . Na 3 PO 4 /Li 2 HPO 4 is the same as PO 3-4 /HPO-4 which is a conjugate acid/base pair, and so is a buffer. 3. When a strong acid is added to a buffer, the H 3 O + will react with the base of the buffer. When a strong base is added to a buffer, the OH-will react with the acid of the buffer. You should be able to write the reactions for this. 4. Buffer capacity of buffer prepared from HA/A-has best buffer capacity at pH=p K a (HA), and the good buffer capacity range is a range of 2 pH units: =p K a (HA)
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