Hint even though this is a titration of a weak base

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Hint: Even though this is a titration of a weak base with a strong acid, pH still equals pK a at halfway to the equivalence point. But in this titration, what is the acid in the buffer system? When you obtain the pKa, you will be determining it for this acid. ½ equivalence point = 2.5 drops pH = 9.2 = pKa Ka = 10^-9.2 = 6.31 * 10^-10 Kb = Kw/Ka Kb = 1*10^-14/6.31*10^-10 = 1.58 * 10^-5 pKb = -log(Kb) = 4.8 Since the pH still equals pKa at ½ equivalence point and the equivalence point is at 5 drops, I was able to use this to determine the pKa of the titration. With a known value of pKa, you can find Ka which would be the value for the acid. Hence, I would have to find Kb (for the base) through a known quantity of Kw. With Kb you can determine pKb in the same method as pKa and Ka.
7 Question 18: Why is the equivalence point acidic for the titration between ammonia and HCl? Hint: Think about what species are present at the equivalence point.
Question 19: Suppose you want to make a buffer solution of pH 8.2 for a clinical physiological experiment. Using Figure 14.9, describe how you would do this. Include the K b of the base used as well as the amount of added HCl.
8 Section F. The Titration of Polyprotic Acids Question 20: You should have curves drawn for the strong acid/strong base, weak acid/strong base, and strong acid/weak base titrations—check your graph to make sure you have distinguished between the curves and have your axes appropriately labeled. Please reference the page in your notebook where this graph is located in response to this question. Remember to attach your titration curve to the end of this section. This can either be done electronically and inserted below or it can be completed by hand and inserted as the next page of your report. You do not need to respond to this question inside this box. Watch the video associated with this section and record your observations below. It may be helpful to record your observation in a table. Read through this section in your Chemtrek and follow up with your TA with any questions. Briefly summarize the section. This experiment conducts a polyprotic acid serial titration between H3PO4 and NaOH. Well 1 pH = 2 Well 2 pH =3 Well 3 pH = 4 Well 4 pH = 3

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