Piperazine, C4H10N2, is a diprotic weak base (pKb1 = 4.22 and pKb2 = 8.67). A sample of piperazine is dissolved in 100.0 mL of water and titrated with 0.500 M HCl. It takes 48.00 mL of HCl to reach the second equivalence point.
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a) What was the original concentration of the piperazine solution?
b) Calculate the pH after the following amounts of HCl have been added: 0 mL, 12.00mL, 24.00mL,36.00mL, 48.00mL, and 60.00mL
c) Sketch the titration curve for this titration
d) Which of the following indicators could be used to detect the first equivalence point? The second?
Indicator Ka Color Change
______________________________________________________________
Bromocresol green 2.5 x 10^-5 yellow => blue-green
Phenol Red 2.5 x 10^-8 yellow => red
Methyl Yellow 3.5 x 10^-4 red => yellow
Alizarin Yellow 8.9 x 10^-12 yellow => red
Piperazine, C4H10N2, is a diprotic weak base (pKb1 = 4.22 and pKb2 = 8.67). A sample of piperazine is dissolved in 100.0 mL of water and titrated with 0.500 M HCl. It takes 48.00 mL of HCl to reach the second equivalence point.
SHOW ALL WORK
a) What was the original concentration of the piperazine solution?
b) Calculate the pH after the following amounts of HCl have been added: 0 mL, 12.00mL, 24.00mL,36.00mL, 48.00mL, and 60.00mL
c) Sketch the titration curve for this titration
d) Which of the following indicators could be used to detect the first equivalence point? The second?
Indicator Ka Color Change
______________________________________________________________
Bromocresol green 2.5 x 10^-5 yellow => blue-green
Phenol Red 2.5 x 10^-8 yellow => red
Methyl Yellow 3.5 x 10^-4 red => yellow
Alizarin Yellow 8.9 x 10^-12 yellow => red
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