Acetic acid, HC2H3O2 (weak acid), with ammonia, NH3 (weak base)
A pH Sensor will be placed in one of the acid solutions. A solution of one of the bases will slowly drip from a buret into the acid solution at a constant rate. As base is added to the acid, you should see a gradual change in pH until the solution gets close to the equivalence point. At the equivalence point, equal numbers of moles of acid and base have been added. Near the equivalence point, a rapid change in pH occurs. Beyond the equivalence point, where more base has been added than acid, you should again observe more gradual changes in pH. A titration curve is normally a plot of pH versus volume of titrant. In this experiment, however, we will monitor and plot pH versus time, and assume that time is proportional to volume of base. The volume being delivered by the buret per unit time should be nearly constant.
One objective of this lab is to observe differences in shapes of titration curves when various strengths of acids and bases are combined. You will also learn about the function and selection of appropriate acid-base indicators in this experiment. In order to do several other experiments in this lab manual, you need to be able to interpret the shape of a titration curve.
In this experiment, you will
Observe differences in shapes of titration curves when various strengths of acids and bases are combined.
Learn about the function and selection of appropriate acid-base indicators.
Learn how to interpret the shape of a titration curve.
Sensors and Equipment
This experiment features the following Vernier sensors and equipment.