PLEASE PROVIDE EXPLANATION FOR EACH SOLUTION FOR PARTS A-F (12 pts - 2 pts each)

Question

PLEASE PROVIDE EXPLANATION FOR EACH SOLUTION FOR PARTS A-F

(12 pts - 2 pts each) 8.) Using the titration curve provided below, answer questions a-f. Place your answers in the blanks provided. Volume of HCI (20) added (ml) a.) What is the initial pH of the aqueous solution before any HCI (aq) is added? 1,2 b.) What is the pH at the equivalence point in this titration? 5.a c.) What is the volume of HCI (aq) solution added to reach the equivalence point in the titration? 30. m 15 MC d.) At what volume of added HCI (aq) solution does pH = 14 - pK? pka e.) At what volume of added HCI (aq) solution is the pH calculated by solving an equilibrium problem (ICE) based on the K, and concentration of the conjugate acid? 30, na f.) Which of the following indicators would be the best choice for the titration described above? Circle your answer below: bromocresol green (pK, = 4.9) p-nitrophenol (pK, =7.2) phenolphthalein (pK, = 9.0)

Explanation / Answer

a) Initial pH corresponds to VHCl = 0ml on the plot which is 11.2

b)Equivalence point occurs, here, when the pH of solution drops suddenly. pH when the drop is nearly half of the sudden pH drop in pH is taken as equivalence point pH which is 5.2 (Sudden drop in pH is around 6 units, so pH at half os sudden drop pH that is when drop is nearly 3 units corresponds to equivalence point pH. This is 5.2)

c) Volume at which pH drops all of a sudden is equivalence point volume, which is 30 mL here.

d) Half of equivalence point volume that is 30/2 = 15ml.

e)This is done when whole of the base has converted to acid form and now pH is decided by the acid form. This occurs at the equivalence point that is at 30 ml.

f)Indicator whose pKa is closest to the equivalence point pH will be most suitable as colour change of the indicator will happen around its pKa, so if the equivalence point and pKa are close end point marked by colour change will be more accurate and will give better idea of equivalence point. So bromocresol blue which has pKa 4.9,closest to the equivalence point pH 5.2, is best option.

Comment in case of any doubt.

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