Piperazine, C4H10N2, is adiprotic weak base (pkb1=4.22 and pkb2=8.67.A sample of piperazine is dissolved in 100.0 mL of water andtitrated with .500 M HCl. It takes 48.00 mL of HCl to reach thesecond equivalence point. What was the orginal concentration of the piperazinesolution? Thanks and please show how you got your answer :) Piperazine, C4H10N2, is adiprotic weak base (pkb1=4.22 and pkb2=8.67.A sample of piperazine is dissolved in 100.0 mL of water andtitrated with .500 M HCl. It takes 48.00 mL of HCl to reach thesecond equivalence point. What was the orginal concentration of the piperazinesolution? Thanks and please show how you got your answer :)
Explanation / Answer
Chemical reaction: C4H10N2 (aq) + H+ (aq) ----------------> C4H10N2H+(aq) ( First equivalence point) C4H10N2H+(aq) + H+ (aq) ----------------> C4H10N2H2+(aq) (Second equivalence point) From the balanced chemical reacion one mole of the acid isreacting with one mole of the base. We know that the volume required to reach the first equivalence point and thesecond equivalence point is same. Hence the volume of HCl at the first equivalencepoint = 24.0 mL Data: [HCl] = 0.500 M VHCl = 24.0 mL =0.024 L Number of moles of HCl = 0.024 L * 0.500 M =0.012 moles Concentration of Piperazine in 100 mL = 0.012 moles /0.1 L = 0.12 M