Question

A 0.352g sample of an antacid is dissolved in water. To it is added 40.00ml of 0.141M HCl solution?

The solution is heated to drive off any CO2 gas. It is then back titrated to endpoint with 8.92ml of a 0.203M solution of NaOH. How many moles of base were in the original sample of the antacid. How many millimoles?

Answer 1

millimoles of NaOH = 8.92 x 0.203 = 1.81

millimoles of HCl = 40 x 0.141 = 5.64

millimoles that actually reacted with antaacid = 5.64 -1.81

                                                                    = 3.83

millimoles of base = 3.83

moles = 3.83 x 10^-3