Question

You have a 0.025 L solution of piperazine (perhydro-1,4-diazine), a weak dibasic base. The Ka values for its conjugate acid are 4.65*10-6 and 1.86*10-10 (in a solution with an ionic strength of zero). You would like to know the concentration of your solution and decide to titrate with HCl. You make a 0.10 M solution of the acid and use methyl orange as an indicator. You reach the endpoint after adding 54.16 mL of your HCl solution.

(c) How many moles of piperazine were in your initial solution?

(d) What was the concentration of your initial solution?

e) What was the pH of your initial solution?

(f) What was the pH at your first equivalence point

(h) What was the pH at your second equivalence point?

Answer 1

i methyl orange end pour Candre end point red color, PH23-7) prai 2 - log (465x100) s.33 pr at end point (pica , so piperazine (6) reacts with 2 moles He and converted to fully protonated form (tefe u to piperazine t aut Piperazine-ent- B + 2ut - BHI moles of piperazine a Ixmoles of Heladdet mxo-0266 2 I x 0-10m x 54 16 ml x 103 moles of popevzne a To.0027 more Meram o 10832 m 20-4M calculate Ko from Ka K6 x Kag & Ko K6 x 1.86 x 10 to 2 1.000 Loly 2) 1 a 5-38x665.

B the 011m 1 But tot 0 0 XX E o lly قولكم ( عدوهم - kb a Cont) [on) CB) 5.38X105 2x² O'lim Cont) 2 x 0.0024m por 2.62 pH z 14.00 - 2.622 [11-38] pot at Aust equivalence point here all Base (3) antha is converted to But BHT a is Amphotenc facts as aod & base) so pha pical + phar puz -log (kai) + -log(kan) 2 Z -log(4-60x106) + -log(-86x160 2 5-333 9.730 2 7.53152 0 7.532)

n) point at second equivalence - all B (piparazine) piperazine 24t (Bit) a converted to [Bryta] a moles piperazine Total volume O-0027 moles 0-625L +5446 mx 1632 ML 0034 m. B4+2 2 BH + et 20-034 G0-034 « 1 Свн*) си") (BH +2] 4-658106 a x² 0-634-x z) x +4-65X106 - 0.1581415.o. ose quadratic equation Solver, - we will get x a Cat) 0.0004om py 2 tog Cat 2 log [o-20040 M) a 13-40)