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Lecture Room Size pH Meter

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.