Piperazine can be used as an anthelmintic (a drug that expels parasitic worms from the body). It is a dibasic compound and has 2 pKb’s as shown below: Consider the titration of 50.00 mL of 0.05000 M piperazine is titrated with 0.1250 M HCl. What is the pH after 15.00 mL of HCl have been added?

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Piperazine can be used as an anthelmintic (a drug that expels parasitic worms from the body).  It is a dibasic compound and has 2 pKb’s as shown below:

Consider the titration of 50.00 mL of 0.05000 M piperazine is titrated with 0.1250 M HCl.  What is the pH after 15.00 mL of HCl have been added?

This diagram illustrates the chemical equilibrium and dissociation constants for piperazine and its hydrochloride forms.

1. **Piperazine (B)**: The structure on the far left is piperazine, a cyclic compound with two nitrogen (NH) groups.

2. **Piperazine Hydrochloride (BH⁺)**: The central structure is piperazine hydrochloride, where one nitrogen is protonated (NH₂⁺Cl⁻). It forms from piperazine with a dissociation constant \( K_{b1} = 5.37 \times 10^{-5} \).

3. **Piperazine Dihydrochloride (BH₂²⁺)**: The structure on the far right is piperazine dihydrochloride, with both nitrogen atoms protonated (\( \text{Cl}^- \text{H}_2\text{N}  \; \text{and}  \; \text{NH}_2^+\text{Cl}^- \)). It forms from piperazine hydrochloride with a dissociation constant \( K_{b2} = 2.15 \times 10^{-9} \).

This sequence of reactions shows the stepwise protonation of piperazine in the presence of hydrochloric acid, highlighting the relative strengths of the equilibria involved.
Transcribed Image Text:This diagram illustrates the chemical equilibrium and dissociation constants for piperazine and its hydrochloride forms. 1. **Piperazine (B)**: The structure on the far left is piperazine, a cyclic compound with two nitrogen (NH) groups. 2. **Piperazine Hydrochloride (BH⁺)**: The central structure is piperazine hydrochloride, where one nitrogen is protonated (NH₂⁺Cl⁻). It forms from piperazine with a dissociation constant \( K_{b1} = 5.37 \times 10^{-5} \). 3. **Piperazine Dihydrochloride (BH₂²⁺)**: The structure on the far right is piperazine dihydrochloride, with both nitrogen atoms protonated (\( \text{Cl}^- \text{H}_2\text{N} \; \text{and} \; \text{NH}_2^+\text{Cl}^- \)). It forms from piperazine hydrochloride with a dissociation constant \( K_{b2} = 2.15 \times 10^{-9} \). This sequence of reactions shows the stepwise protonation of piperazine in the presence of hydrochloric acid, highlighting the relative strengths of the equilibria involved.
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