Electrolytic Titration of Ba(OH)2 with H2SO4
A titration that uses the conductivity of a solution to measure the endpoint.
Chemicals and Equipment Needed
 d-H2O
 Ba(OH)2 • 8 H2O – E2
 1 M H2SO4 – J1
 250 mL beaker – Q2
 25 mL buret – P5
 Light bulb conductivity tester – J1
 Short ringstand – J1
 Buret clamp or small three finger clamp – J2
 Small stirbar – U1
 Stirplate – A4
Preparation
 Fill buret with 1 M H2SO4, attach to short ringstand. Remove one light bulb from the conductivity
apparatus and attach to the same ringstand.
 Weigh out 0.65 g Ba(OH)2 • 8 H2O into one 250 mL beaker, dilute to 100 mL with d-H2O, and add
stirbar. The solid will barely dissolve.
 Place the beaker on top of the stirplate, and maneuver the parts of the demonstration so that the
prongs of the connectivity tester are submerged, the stirbar can move freely, and the buret can easily
drip into the beaker. This is difficult to arrange properly. Refer to photo for correct placement.
Presentation
 Let instructor know that the titration requires ~5 mL H2SO4.
 Plug in the conductivity tester (light bulb will light), and turn on stirplate. Begin titrating with H 2SO4.
The light will gradually dim until it goes out completely:
Ba2+ (aq) + 2 OH- (aq) + 2 H+ (aq) + SO42- (aq)  BaSO4 (s) + 2 H2O (ℓ)

Addition of excess H2SO4 will cause the bulb to light up again.
Clean-Up
 Barium CANNOT go down the drain. Neutralize the solution with some 6 M NH3 and pour into the
white waste container, along with rinses from the electrodes of the conductivity tester, and rinses of the
beaker.
NOTES: The grey stirplate with the white surface is a good size for making sure all the parts fit together. It
takes some rearrangement and creativity to get everything in the right place.
Revised Spring 2015
AMM