Signed as Henry Rivera t T ration Curve for Piperazine and HCI 3 of 7 urve for P

Question

Signed as Henry Rivera t T ration Curve for Piperazine and HCI 3 of 7 urve for Piperazine and HCI A 1.00gsample of piperazine hexahydrate is dssolved in enough water to produce 1000 ml, of solution andis ttrated witho 500 M HCl IN(C Hs)NH. is a dpratic weak base used Part A inhibitor and an insecticide and has the What is the initial pH of the solution, before any titantis added? 4.22 Express your answer numerically with two digits ater the decimal point. pKia 8.67 reactions of this base in water, it can be reviate the formula as Pip: PipH, e used commercially hexahydrate with the Hirts My Answers Give Up Review part Part B The percent neutralization points for a titrationindicate the percent of the reagent that has reacted For example, a the 25% neutralization point for 75% (0.75 x Pipl of the base remains and 25% is neutralized to fom PipH piperazine, Calculate the pH at the 25% 50% and 75% neutralzation points of the first neutralization, respectively Enter the pH at the 25%, 50s, and T5% neutralization points to two decimal places separated by commas.

Explanation / Answer

Moles of piperzine = 1 g / 196 g/mol == 0.00510 mol

Molarity of piperzine = 0.00510 mol / 0.1 L = 0.0510 M

ICE tabel:

B + H2O <----------> BH+ + OH-

0.0510 -x x x

kb1  = x2 / 0.0510 -x

0.215x10-8  = x2 / 0.0510 -x

x= 0.105x10-4 M

pOH = -log (0.105x10-4 )

= 4.98

pH = 14-pOH = 14-4.98 == 9.02

(B)

Volume of HCl is;

V x 0.5 M = 2 x100 mLx 0.0510 M

V = 20.4 mL

At 25%:

Volume of acid = 0.25 x 20.4 =5.1 mL

Moles of acid = 5.1 mL x 0.5 M ==0.00255 mMoles

Moles of B = 0.00510 - 0.00255 ==0.00255 moles

conc of B = 0.00255 moles / (100+5.1) mL ==0.0243 M

Conc of BH+ == 0.00255 moles / (100+5.1) mL ==0.0243 M

Ka2 = KW / kb1

= 4.65 x10-6

pH = pKa2 + log (B/BH+ )

= 5.3

Similarly practice for 50% and 75% conversion

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