Piperazine, HN(C4H8)NH, is a diprotic weak base used as a corrosion inhibitor an

ID: 831555 • Letter: P

Question

Piperazine, HN(C4H8)NH, is a diprotic weak base used as a corrosion inhibitor and an insecticide and has the following properties:

pKb1=4.22pKb2=8.67

For writing the reactions of this base in water, it can be helpful to abbreviate the formula as Pip:

Pip+H2OPipH++H2O??PipH++OH?PipH22++OH?

The piperazine used commercially is a hexahydrate with the formula C4H10N2?6H2O.

A 1.00-g sample of piperazine hexahydrate is dissolved in enough water to produce 100.0 mL of solution and is titrated with 0.500 M HCl.

What volume of 0.500 M HCl is needed to reach the first equivalence point?

Part (c):

POH = 0.5(Pkb1+PKb2) = 0.5(4.22+8.67) = 6.445

PH = 14-POH = 7.555