Lecture Room Size pH Meter
Materials
Large Display
Old Style pH Meter with "Recorder Out" plugs and pH Electrode
3V Step-up Voltage box with red and back leads in and out
pH 7 and pH 10 buffers
250 mL (or larger) Beaker
Magnetic Stir Bar
Magnetic Stir Plate
0.1M Hydrochloric Acid
0.1M Sodium Hydroxide
Bottle of DI water
25 mL Graduated Cylinder
Phenolphthalein Indicator
Buret on a ring stand
Funnel with a tip that fits inside the buret (for filling Buret)
Gloves and Goggles
Procedure
- From the recorder output of the pH meter, plug in leads running to the mini-amp "millivolts in" plugs.
- From the "0 to 3 out" plugs, run leads to the "U" input plugs on the base unit. Be sure the 3V module is in place. Careful not to cross the "+" and "-" leads.
- Settings on the base unit are center zero and direct current (bottom front right corner).
- Both the mini-amp and base unit must be turned on.
- In a 250ml beaker, add 25ml acid, 25ml water, a stir bar, and two drops of phenolphthalein indicator.
- Place beaker on a stir motor and mount the buret and electrode in appropriate positions; check to be sure that the electrode cannot be damaged by the stirring bar.
- Fill the buret with sodium hydroxide solution and titrate. The acid and base solutions are equimolar.